Cellulitis & Erysipelas in Primary Care: Assessment, Treatment & Clinical Decision-Making for New Nurse Practitioners
Cellulitis is one of the most common skin infections seen in primary care, but deciding who can be treated as an outpatient versus who needs hospitalization can be challenging. In this video, I walk through a practical approach to evaluating cellulitis, recognizing red flags, choosing treatment, and applying clinical reasoning to real-world patient care.
Editor's Note (Reviewed & Updated July 2026): This article and accompanying video were reviewed in July 2026 to ensure they remain accurate and aligned with current evidence and primary care practice. While the video was originally recorded earlier, the clinical principles and decision-making discussed remain relevant, and the written content has been updated with current recommendations and additional context where appropriate.
Watch
In this episode, you'll learn:
How to recognize common features of cellulitis
The difference between cellulitis and erysipelas
Important risk factors that change management
When outpatient treatment is appropriate
When hospitalization should be considered
Common cellulitis mimics to avoid missing
When it comes to cellulitis, there’s a lot to think about. Most of the new nurse practitioners I mentor have textbook knowledge and clinical judgment, but there are a few steps needed to connect the dots in real-world practice.
Key Takeaways
Assess severity before choosing antibiotics.
Look for underlying risk factors.
Don't forget tinea pedis.
Reassess patients within 24–48 hours.
Hospitalize patients with systemic illness or concern for deeper infection.
Antibiotic selection depends on whether the infection is purulent or non-purulent, the patient's allergies, MRSA risk factors, and local resistance patterns. Current treatment recommendations should always be confirmed using an evidence-based resource such as IDSA guidelines, Sanford Guide or your institution's preferred antimicrobial reference
Frequently Asked Questions
What is the difference between cellulitis and erysipelas?
Cellulitis and erysipelas are both bacterial skin infections, but they involve different layers of the skin. Cellulitis affects the deeper dermis and subcutaneous tissue, while erysipelas is a more superficial infection with well-defined, raised borders and often a more rapid onset. Although the distinction can be helpful clinically, both conditions are evaluated similarly and require prompt treatment when a bacterial infection is suspected.
Does every patient with cellulitis need antibiotics?
Most patients with bacterial cellulitis require antibiotics because the infection typically does not resolve on its own. The choice of antibiotic depends on factors such as whether the infection is purulent or nonpurulent, the patient's risk factors for MRSA, medication allergies, local resistance patterns, and the severity of illness. If you're unsure about antibiotic selection, consult current evidence-based guidelines or an antimicrobial reference like the Sanford Guide, which is updated annually and has an app version (no affiliation).
When should cellulitis be hospitalized?
Hospitalization should be considered for patients with signs of systemic illness, rapidly progressing infection, concern for a deep soft tissue infection, inability to tolerate oral antibiotics, significant immunocompromised status, or failure to improve with appropriate outpatient treatment. Clinical judgment is essential, and patients with diabetes, severe edema, or extensive infection may require a lower threshold for emergency department evaluation and possible IV antibiotics.
How long does cellulitis take to improve?
Most patients begin to show signs of improvement within 24 to 48 hours after starting appropriate antibiotics, although redness and swelling may initially appear unchanged or even worsen slightly as inflammation continues. Close follow-up is important to ensure the infection is responding to treatment. If symptoms are rapidly progressing, new systemic symptoms develop, or the affected area continues to expand beyond the expected margins, the patient should be re-evaluated promptly.
What conditions can mimic cellulitis?
Several conditions can resemble cellulitis, making a careful history and physical examination essential. Common mimics include:
Venous stasis dermatitis
Deep vein thrombosis (DVT)
Contact dermatitis
Insect bites
Drug eruptions
Herpes zoster
Erythema migrans (Lyme disease)
Osteomyelitis
Gout (depending on the location and presentation)
Considering the differential diagnosis is especially important when the presentation is atypical, bilateral, recurrent, or not responding to appropriate antibiotic therapy. Please note that these are common mimics but not a complete differential.
Looking for the Cellulitis & Erysipelas Cheat Sheet for Your Desk?
If you'd like a cheat sheet that goes with this video, you can find it inside the Digital NP Binder. Purchase your copy here!
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0:00
well hey there it's liz rohr from real
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world np and you're watching np
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practice made simple the weekly videos
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to help save you time frustration
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and help you learn faster so you can
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take the best care of your patients
0:10
so today i'm going to be talking about
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cellulitis
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and erysepolis i have to think about
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that pronunciation every single time
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um but yeah so i'm going to be talking
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about that presentation
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and i really want to focus on um
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i want to backtrack and say that i have
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been precepting nurse practitioners for
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almost five years now and i i currently
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mentor
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several new nurse practitioners in
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primary care and
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i have to say that nurse practitioners
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as a whole as they're
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new into practice it's overwhelming it's
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a lot of responsibility
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um and i they are very bright and
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they have great resources and most of
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the time what we're doing when we're
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talking together is putting those pieces
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together
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and forming kind of those clinical
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judgment decisions
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um that you can't really get from
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textbooks so that's what i kind of want
1:00
to focus on
1:01
in this video today is talking about
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what are the what is it kind of like
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foundation some foundational knowledge
1:05
about cellulitis
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but also the clinical decision making of
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how it really applies in real world
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practice because that's what i'm here
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for right real world
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uh np practice so yeah so some clinical
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manifestations of cellulitis so
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um and aerospalis you want to think
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about um this is probably not news to
1:21
you but just as a recap
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disclaimer actually before i get started
1:24
into the clinical manifestations is that
1:27
there are many types of cellulitis and
1:29
so peri-orbital cellulitis has very
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specific
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things you want to think about when it
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comes to assessment when it comes to
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treatment
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and additionally there are other types
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of less common places of getting
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cellulitis so
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somebody who has a larger bmi who has a
1:44
panic gets peniculitis
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things like that like those are very
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kind of unique situations to investigate
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further
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primarily what i'm focusing on here has
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to do with lower extremity
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cellulitis because that's like the main
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one that i see in primary care may also
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apply to upper extremity as well
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but anyway so just using your clinical
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judgment and listening to your gut when
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it comes to
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specific types of cellulitis that are
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less common presentations but anyway so
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i'm generally focusing on lower
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extremity cellulitis because that's the
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most common cause
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so some clinical manifestations is it's
Clinical manifestations
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usually the unilateral
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um one-sided edema
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warmth whether it's like slightly warm
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to hot and
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erythema and i want to make a note that
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um there's different skin tones for
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patients right so there's
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that fits patrick scale that one to six
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it talks about um
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you know darker versus lighter skin like
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all the way up the scale
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so depending on the baseline skin tone
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of the patient it's going to appear
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differently right
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so in patients who have a five or six
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skin tone or darker skin tone they might
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appear as hyperpigmentation so
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definitely don't um miss out on that for
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sure and that
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it's not talked about i think enough um
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versus if you have a very light skin
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tone i believe i have type one
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um for me it would be a very like a
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brighter red color
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uh potentially um and so um
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you might also see things like petechiae
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superficial boule and i never say that
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right those
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large blisters um you also may see
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vesicles
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the smaller blisters as well as ecomo
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sees sometimes i don't see that as often
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but i definitely do see the boulet
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and the vesicles for sure
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um you may or may not see fever in
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patients it tends to correlate with more
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clinically ill patients when they have a
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fever
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or things like tachycardia or
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hypotension um
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if you happen to see that those patients
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are a lot more ill and likely need
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hospitalization
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and then when it comes to aerospalis
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versus cellulitis
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aerosplash is more of a superficial
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skin infection whereas the cellulitis
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goes deeper into the towards the fat
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tissue
Aerospalis vs Cellulitis
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and for aerospace you might see a more
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rapid onset
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brighter um more intense symptoms and
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you might see edema of the skin and that
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potential appearance like the
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orange peel because the follicles
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because of the edema and like sharp
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demarcation
4:00
that's a little bit more consistent with
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that i see that less often quite
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honestly than the cellulitis
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and then when it comes to um the
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assessment and the treatment
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cellulitis really breaks down into
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purulent versus non-purulent and there's
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kind of different
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treatment pathways depending on which
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one you're talking about if there's any
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discharge drainage things like that or
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an abscess
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really important to assess is if there's
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any fluctuance so when you're pressing
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down on
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with gloves on on top of the of the area
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you're not getting any of that fluctuate
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sensation because those patients may
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need incision and drainage
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they might need some some other types of
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treatment i'm not really getting into
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abscess in this video
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a couple other things i just want to
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talk about when it comes to cellulitis
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and the conversations that i typically
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have with newer clinicians
Risk Factors
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a couple things to think about so one is
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risk factors another one is
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whether or not they need hospitalization
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um
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choosing the antibiotics and then the
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type of like kind of real world
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management so just to jump in that's the
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rest
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of the stuff i'm going to talk about in
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this video so um risk factors so there's
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a number of risk factors to think about
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which will really inform your plan going
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forward
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so where did this come from so did
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somebody fall
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and they have a trauma to the area and
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then it became infected do they have an
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underlying skin condition like eczema
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psoriasis
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um things like that um do they have
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edema in their lower extremities because
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of um
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uh you know lymphatic impaired lymphatic
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drainage
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venous insufficiency are the
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immunosuppressed in a way like with
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diabetes or hiv or cancer
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things like that um a really uh an
Other Risk Factors
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additional risk factor is obesity and i
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i can't speak to the um to the to the
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actual like mechanism of action there
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maybe just like a correlation that's
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been noted
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um and a really kind of sneaky pearl one
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which you may have heard before
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is um tinia so having tina peters in
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between the toes
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um onychomycosis and the toenails those
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are definitely risk factors for the
5:54
development of a bacterial skin
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infection a cellulitis
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so things to think about like what are
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those risk factors so not only that
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helps you and helps inform the history
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and like what the steps further are like
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was it just an injury
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the injury's going to heal you treat
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that uh treat the cellulitis and it goes
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away
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versus they have diabetes um
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antineapetis do you want to treat them
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for the tinia and then you also want to
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think about um does that increase their
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risk for a more severe infection
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so those are the main things when it
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comes to risk factors which really ties
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into this question of do they need
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hospitalization or not so i want to give
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a patient an example here
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so when i was a newer grad i think i had
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a couple months of experience i don't
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remember exactly how much how long but i
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had a patient
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a white male uh six year old 60ish uh
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year old man and he had diabetes
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uh who's and his a1c was about in the 10
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to 12 range first uh 10 to 12 percent
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persistently he also had lower extremity
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edema um
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on and off uh just idiopathic we've
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worked it up and it was kind of just
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there
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chronic venous insufficiency was
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probably the likely cause he's like oh
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can you just take a look at my foot real
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quick
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um i i fell and i stumbled and i stubbed
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my toe
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and i was like okay that's fine he took
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his off his shoes he takes off his socks
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he rolls up his pant leg
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um and like he had very like light skin
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and so he
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light colored undertone of his skin and
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he had a very bright red
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foot all the way up to his mid shin and
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he had
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a clear injury at his toe and he had
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diabetes
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and um it was very hot it was swollen it
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was very red
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and he um it was malodorous too like
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there was there was
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some kind of smell coming from the from
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the injury
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and so um so i knew that he had some
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sort of bacterial infection
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needed treatment um but i just had this
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gut sensation
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of this is a lot of i see this a lot in
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newer clinicians where it's kind of it's
7:44
a little bit overwhelming to be a new
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provider
7:46
regardless of nurse practitioner or
7:47
otherwise when you go to see a patient
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you're really focused on the symptoms
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the history the assessment
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diagnosis the plan the treatment it's
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kind of hard not to get swept away by
7:57
that
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and so very easily you could say that
7:59
this patient needs antibiotics
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um but it's really important to take
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that pause and i and i had this pause of
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like this gut sensation of like okay
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like
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i probably should have somebody else
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look at this this looks this looks
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really severe
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so um and his vital signs were stable he
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had no fever he felt fine
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aside from being in some pain in his
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foot and i pulled
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my colleague and my uh supervisor at the
8:19
time and they agreed very heartily that
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he needed hospitalization
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and so um so yeah i mentioned that just
8:25
because i
8:26
i remember that that feeling of kind of
8:29
um
8:30
just it's just hard it's hard being a
8:32
new provider
8:33
so that's something to think about is
8:34
one in your decision tree right
8:36
hospitalization or not
8:37
and there isn't really a hard and fast
8:39
like rule but it's kind of more
8:41
along the lines of how severe is it what
8:43
are their risk factors again
8:44
do they have fever tachycardia
8:46
hypotension
8:48
um extremes of age like things like that
8:50
um to really inform your decision
8:52
so um so yeah so looking at the risk
8:55
factors the symptoms whether or not they
8:56
need hospitalization the last kind of
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like two to three things i want to talk
8:59
about
9:00
is like the decision tree of treatment
9:02
so if it's safe to keep them outpatient
9:05
you want to consult whatever resource
9:07
you use to to help with this
9:09
and so there's a variety of resources
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but um i particularly love sanford
9:13
antimicrobial guide and i'm not
9:14
affiliated with them
9:15
in any way i just use it myself and it's
9:18
about thirty dollars a year and you can
9:20
search on their app by type of infection
9:23
include their allergies include their
9:24
risk factors and their recommendations
9:26
for
9:26
which antibiotic for how long et cetera
9:28
et cetera there are other ones out there
9:30
but that's the one that i use the most
9:32
and thinking about like do you need to
9:34
treat for mrsa versus uh
9:36
versus for resistant and bacteria versus
9:38
not
9:39
um yeah and then in terms of like the
9:41
real world implications again another
9:43
thing that i had to catch myself doing
9:44
as a new nurse practitioner as a newer
9:46
provider
9:47
is that it's very easy to say you know
9:49
i've made that decision they're safe to
9:50
go outpatient let's just give them an
9:52
antibiotic and go
9:53
but really we have to still exercise a
9:55
lot of caution with these patients and
9:56
so
9:57
generally speaking i'll bring my
9:58
patients back in the first 24 to 48
10:01
hours of starting antibiotics
10:02
to monitor the progression and see if
10:04
it's getting better or if it's getting
10:05
worse
10:06
always giving those alarm signs in
10:08
between of like if you develop any of
10:09
these alarming things then please seek
10:11
care or please contact the clinic
Hospitalization
10:14
and typically um this is consensus
10:16
practice of
10:17
that close follow-up but also doing an
10:19
outline of the area
10:21
right with a skin marking pen to make
10:23
sure that it's not extending beyond
10:25
those margins
10:26
because if it is then those patients
10:27
actually might need iv antibiotics
10:29
instead of oral
10:30
therapy or they might need an antibiotic
10:32
change but typically if it's extending
10:34
within that period of time
10:35
i'll typically refer them for
10:37
hospitalization for assessment for iv
10:39
antibiotics and
10:40
it depends on on the type of infection
10:42
and the risk factors like
10:43
if they even need to be admitted or if
10:44
they just stay for a couple of doses of
10:47
antibiotics so
10:48
so yeah and then the last thing i just
Other Considerations
10:50
want to wrap with i started with kind of
10:52
things to watch out for in terms of
10:54
periorbital cellulitis is a little bit
10:56
different you're not necessarily going
10:57
to mark around the eye
10:58
there's some other considerations right
11:00
and there's there's also a wide
11:01
differential base as well as alarm signs
11:04
and symptoms to watch out for in
11:05
addition to the ones that i've already
11:06
mentioned
11:06
so things like crepitus if it appears
11:08
gangrenous like if they seem unstable
11:11
i'm trusting your clinical judgment here
11:12
to like look at a patient be able to to
11:14
see those things but just
11:16
definitely things to keep in mind a
11:17
couple of sneaky ones that will present
11:19
as
11:20
um similarly to a cellulitis a lower
11:23
extremity cellulitis in particular
11:25
drug reactions uh erythema migrants
11:29
especially if it has central clearing
11:30
because or the aerocephalus can have
11:31
that um central clearing sometimes
11:34
um herpes again can have those little
11:35
vesicles um
11:37
and then osteomyelitis so so to kind of
11:39
go back to that patient i
11:40
sent him to the er and he got admitted
11:43
and he was there for actually a couple
11:44
of months because he ended up
11:45
having um an osteomyelitis he needed an
11:48
amputation he needed long-term iv
11:50
antibiotics he actually ended up on in
11:51
renal failure because of
11:53
a variety of things but um but yeah so
11:55
that's definitely a risk factor that you
11:57
want to think about
11:58
um also contact dermatitis dvts
12:02
stasis dermatitis insect bites and then
12:04
another one is a
12:05
so those are things to think about not
12:07
comprehensive of course so definitely
12:08
utilize your resources
12:10
but animal bites are another separate
12:12
category those have very particular
12:14
things to think about too so
12:15
anyway that is hopefully like a primer
12:17
in cellulitis or a refresher in
12:19
cellulitis
12:20
but definitely consult with your
12:21
resources to get that full picture and
12:23
always consult if you have any questions
12:25
because i still consult too especially
12:27
if you're not sure to send somebody to
12:28
the er or not
12:29
especially if they don't have insurance
12:31
they don't want to go there's covid you
12:32
know so
12:33
um there's no there's no harm there's no
12:35
shame in consulting with other people
12:37
to make sure that you're really kind of
12:39
given the best care for your patients so
12:40
if you have not gotten your copy of the
12:42
ultimate resource guide for the new np
12:44
head over to realworldnp.com guide it's
12:46
my favorite resources
12:47
all the ones that i use um in my day to
12:49
day practice in primary care
12:50
you'll also get these videos sent
12:52
straight to your inbox every week with
12:53
notes from me
12:54
patient stories and bonus content that i
12:56
really just don't share anywhere else
12:58
thank you again so much for watching
12:59
hang in there and i'll see you soon
13:12
you
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