The first antibiotics were discovered in 1928, and ever since, this class of drug has revolutionized how we treat a wide range of infections and illnesses caused by bacteria.
Today, antibiotics are still the best approach to combating cellulitis, which is a common bacterial infection of the skin and soft tissue.
If you are diagnosed with cellulitis, you will almost certainly be prescribed an antibiotic.
And in most cases, you’ll start to see your cellulitis shrink or even disappear within just a few days of starting this antibiotic treatment.
In this article I’ll review what cellulitis is, including its major symptoms and causes.
I’ll discuss how doctors use antibiotics to combat cellulitis, including which antibiotics they prefer.
I’ll also overview additional treatments and go over when to talk to your medical provider about cellulitis.
What Is Cellulitis?
Cellulitis usually appears as a spreading, reddish-pink lesion on your body.
This cellulitis lesion will feel warm, tender and swollen to the touch.
It occurs in an estimated 14.5 million cases per year in the United States.
Cellulitis primarily affects the middle layer of the skin, called the dermis.
This is one big way that cellulitis differs from other inflammatory skin disorders like eczema and psoriasis, which tend to affect the upper level of the skin.
To diagnose cellulitis, your health care provider will look to rule out other diseases, including deeper skin and joint disorders like necrotizing fasciitis and septic arthritis.
Your clinician will also take a medical history, and examine how well your lesions fit with cellulitis’s classic visual types and symptoms.
From there, patients will typically be prescribed a course of oral antibiotics to take at home as the first line of treatment.
When you have cellulitis, your body’s immune system is working to fight off an invading bacteria strain after that bacteria has infected the body through a skin wound.
The immune response itself is responsible for some of the inflammation and discomfort associated with cellulitis infections.
The most typical symptoms of cellulitis include:
- Skin warmth
Cellulitis almost never appears across multiple regions of the body.
Adults often develop cellulitis on a single lower leg, for instance, but not on both legs.
Children, meanwhile, tend to develop cellulitis on the face or neck.
Some cellulitis infections are classified as “purulent.”
This means that the inflamed tissue is accompanied by swollen pus buildups (called abscesses) that need to be drained under the direction of a healthcare provider.
Doctors will also classify cellulitis based on whether it appears to be localized (e.g. confined to one area of the skin) or systemic.
Systemic cellulitis is an infection that has spread to affect other systems of the body, and is marked by symptoms like fevers, abnormal heart rate, or abnormal breathing.
You should see a healthcare provider if you think you have any symptoms of cellulitis.
The condition is most easily treated when caught early.
If left untreated, cellulitis can lead to serious complications.
- Blood infection (sepsis)
- Bone infection (osteomyelitis)
- Inflammation of the lymph vessels (lymphangitis)
- Inflammation of the heart (endocarditis)
- Infection of the membranes covering the brain and spinal cord (meningitis)
- Tissue death (gangrene)
Cellulitis is usually caused when bacteria enters into lower levels of the skin through a skin wound or rupture.
Once there, it then begins to infect and inflame the surrounding tissue.
Various strains of Streptococcus (strep) and Staphylococcus (staph) bacteria cause most cases of cellulitis.
The wounds that lead to cellulitis infections can be big or obvious; for example, they could be open sores, severe burns, surgical grafts, or drug injections.
But cellulitis can also develop from bacteria infiltrating tiny cuts, scratches, or bug bites.
Cracks in the skin caused by eczema, athlete’s foot, or other skin disorders can also create the conditions for cellulitis.
And sometimes there’s no skin wound at all.
In these cases, cellulitis-causing bacteria has spread to the dermis after jumping from other infected systems, like the sinuses.
Cellulitis affects people of all ages, races, and genders.
But people with weaker immune systems are at risk for more serious complications from cellulitis.
This could be due to many factors, including old age, excess weight, cancer treatment, or chronic conditions like diabetes.
Antibiotics for Cellulitis
As soon as your medical provider identifies that you have a probable case of cellulitis, they will likely prescribe you a course of oral antibiotics, a common class of medications that you can take by mouth at home.
Today, the typical course of antibiotics for cellulitis takes around 5 days, but in some cases you may be taking antibiotics for a week or 10 days.
As a cellulitis patient, it’s important to always complete your entire course of oral antibiotics treatment, even if symptoms disappear within the first few days.
Even without ongoing symptoms, there’s always a chance that some of the bacteria hasn’t yet been killed off and that cellulitis could then come back just as strong, or stronger, than before.
In the US, there is no one gold-standard, first-choice antibiotic for cellulitis.
Antibiotic treatment options will vary for cellulitis depending on how early on it has been caught.
Relatedly, medication choice will vary depending on if the cellulitis infection is:
- Localized or systemic
- Purulent or non-purulent
- Pediatric (occurring in kids, often on the head or neck) or adult.
- History of MRSA or MSSA
In general, for most infections that are caught early, the aim is to prescribe an antibiotic that covers the most common strains of cellulitis-causing streptococcus and staphylococcus bacteria.
From there, healthcare providers have a number of different options to choose from.
Today, some of the most common “first-line” antibiotics prescribed for cellulitis include:
- Cephalosporins (including cephalexin)
In most cases this initial treatment of oral antibiotics begins to clear up infection symptoms within 24 to 48 hours.
But in around 18% of cases, patients’ first course of treatment isn’t effective enough in lessening their symptoms.
If you don’t see progress within 2 to 3 days, you should seek immediate medical attention.
One reason why these first-line treatments may fail is if the bacteria driving your infection is resistant to the most commonly prescribed oral antibiotics.
This is the case, for instance, in cellulitis caused by methicillin-resistant staph aureus (MRSA).
Or it may be the case that your immune system itself has been compromised in a way that makes treatment more difficult.
If it seems like your initial treatment isn’t working, your medical provider may switch you to a different oral antibiotic that combats a different range of bacteria.
They may also order diagnostic tests like a blood culture or a biopsy to better pinpoint the kind of bacteria causing the cellulitis infection, which can help them choose a more effective antibiotic.
If at any point during your first or second course of oral antibiotics, you begin to show symptoms of a severe or systemic cellulitis infection, your health care provider may decide to take a different approach.
They may escalate you to additional, more intensive medical treatments.
Most cases of cellulitis clear up from taking oral antibiotics at home over the course of a week or 10 days.
But more severe or threatening cases of cellulitis may require treatment at a hospital over the course of several days.
There, staff will administer a more intensive course of antibiotics intravenously (through a vein), using an IV drip into the bloodstream.
Cellulitis patients who are immunocompromised, have difficulty taking oral medications, or are experiencing a kind of orbital cellulitis that directly threatens vision may progress immediately to systemic antibiotic treatments.
Approximately 4.5% of the 14.5 million annual cellulitis cases in the US result in hospitalization.
A hospital stay for this so-called “systemic antibiotic” typically lasts about a week.
These hospitalizations allow medical staff to both administer the stronger antibiotic infusions safely, as well as monitor patients for more severe complications and for pain management.
Some medical systems have also launched trial programs that allow these treatments to be administered by traveling medical staff in the comfort of patients’ own homes.
Some patients can develop multiple cases of cellulitis a year.
In these cases, research shows that taking a low-dose antibiotic preventatively can help ward off future infections.
People with chronic conditions like kidney disease, diabetes, liver disease, lymphedema may particularly benefit from this approach because of the way these diseases make it easier for bacteria to get inside your body, or reduce your immune system’s response.
When to See a Medical Provider
You should see a healthcare provider if you think you have any symptoms of cellulitis.
You should also stay in contact with your health care provider while completing your course of oral antibiotics.
They will want to know if your cellulitis does not begin to get better after the first 48 or 72 hours, or if it continues to spread.
And they will also want to know if you develop any new symptoms, such as
- Persistent fever
- Blistering over the cellulitis
- Red streaks that spread
In these cases the doctors may try a different antibiotic, or start you on an IV drip.
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Frequently Asked Questions
K Health articles are all written and reviewed by MDs, PhDs, NPs, or PharmDs and are for informational purposes only. This information does not constitute and should not be relied on for professional medical advice. Always talk to your doctor about the risks and benefits of any treatment.
K Health has strict sourcing guidelines and relies on peer-reviewed studies, academic research institutions, and medical associations. We avoid using tertiary references.
Cellulitis: Who gets and causes. (N.D.).
Cellulitis: Self Care (N.D).
Cellulitis: Overview. (N.D.)
Clinical Guidelines for the Antibiotic Treatment for Community-Acquired Skin and Soft Tissue Infection. (2017).