Perianal Strep: Symptoms, What It Looks Like, Treatment and How It Differs From Diaper Rash

Perianal strep is a group A strep skin infection around the anus, most common in children 6 months to 10 years old, that causes a bright red, sharply bordered rash, itching and painful poops and needs a doctor’s swab and prescription antibiotics.

If your child’s red bottom just will not clear up with diaper cream, or pooping suddenly hurts, perianal strep is one possibility worth asking your pediatrician about. It is not rare, easy to mistake for an ordinary rash, and very treatable once it is found.

Below: what it looks like, how it compares with other bottom rashes, how it is tested and treated, and how to stop it spreading or coming back.

What Is Perianal Strep?

It is easy to mistake for diaper rash. A 2021 systematic review in the European Journal of Pediatrics (Gualtieri and colleagues) found that in 65% of reported cases, it took 3 weeks or more to reach the right diagnosis.

Perianal Strep Symptoms and What It Looks Like

• A bright red ring: the AAP describes the rash as usually looking like a bright red ring around the anus. StatPearls notes the redness has well-defined edges.
• How far it spreads: the 2021 review describes sharply demarcated redness extending about 2 to 4 cm (roughly 1 to 1.5 inches) around the anus.
• Itching: in one study summarized by the American Academy of Family Physicians (AAFP), 78% of children had itching around the anus.
• Pain, especially when pooping: the same AAFP summary reports rectal pain in 52%. StatPearls lists pain with bowel movements, which can lead to constipation.
• Blood-streaked stool: about one third of children in that study (35%) had streaks of blood in their stool.
• Other skin changes: AAFP notes small cracks (fissures), mucus-like discharge and yellow crusting in some children.
• Genital involvement: AAFP says the rash may spread to the penis or vulva. The 2021 review found genital involvement in slightly over 10% of cases.

Fever is uncommon. StatPearls and AAFP both describe a lack of whole-body symptoms in most children, although MedlinePlus (NIH) lists fever as a possible symptom.

Who Gets It and How Common Is It?

What Causes It and How It Spreads

The cause is group A Streptococcus bacteria. The CDC calls these bacteria very contagious and notes that strep throat often spreads within households and in crowded settings such as daycare centers and schools.

For perianal strep, StatPearls describes a likely route of self-spread: bacteria move from the mouth, nose or throat to the bottom through fingers, or are swallowed and passed in stool. MedlinePlus says it often appears during or after strep throat or impetigo, and can start when a child wipes or scratches with fingers carrying bacteria from the mouth or nose.

• The throat connection: StatPearls cites data in which 92% of children diagnosed had group A strep in the throat at the same time. The 2021 review found 63% of tested children carried strep in the throat without throat symptoms.
• Family spread: AAFP reports spread within the family in 50% of possible cases in one study.
• Shared surfaces: StatPearls says objects such as toilet seats and bathtubs may play a role, with higher rates within families and daycare centers.

Strep vs Diaper Rash, Yeast Rash and Pinworms

This table compares common causes of a red or itchy bottom. It is a guide for knowing when to call, not a way to diagnose at home.

The clue many parents notice first is that the rash does not respond to the usual diaper creams. AAFP notes that antifungal creams, steroid creams and pinworm medicines often fail or make symptoms worse, which delays the right diagnosis. The AAP’s diaper rash page also says bright red skin around the anus may suggest strep.

StatPearls lists other lookalikes doctors consider, including psoriasis and atopic dermatitis (eczema). See also diaper rash vs yeast infection, baby heat rash and teething rash.

How Doctors Diagnose It

• Skin swab: the AAP says perianal strep is diagnosed with a skin swab. AAFP says a rapid strep test or a culture of the perianal area can confirm it.
• Culture: StatPearls says a definitive diagnosis comes from a bacterial culture of a swab from the affected area.
• Throat swab: MedlinePlus lists a throat culture among possible tests.
• Urine test: StatPearls recommends a urinalysis to watch for post-streptococcal glomerulonephritis, a rare kidney complication of strep.

The 2021 review pooled three studies of 247 children comparing rapid tests with culture. A positive rapid test was right about 80% of the time and a negative rapid test about 96% of the time, so your doctor may still send a culture depending on the result and how the rash looks.

Treatment: Antibiotics and What to Expect

Perianal strep is treated with antibiotics prescribed by your child’s doctor. Details vary by source:

• Oral antibiotics first: StatPearls calls oral antibiotics first-line and says the most successful regimens combine an oral antibiotic with a topical one. MedlinePlus says penicillin is the antibiotic most often used in children. AAFP notes amoxicillin is often better tolerated because the liquid tastes better.
• Topical medicine as an add-on: mupirocin ointment is a common example (MedlinePlus, AAFP). MedlinePlus says topical medicine should not be the only treatment. StatPearls notes topical treatment alone may be used only for minor cases.
• Penicillin allergy: StatPearls lists alternatives, including erythromycin, clindamycin and cephalosporins.
• How long: MedlinePlus says about 10 days, depending on how quickly your child responds. AAFP describes a 10-day course. StatPearls gives 14 to 21 days. Follow the length your doctor prescribes.

Finish every dose, even when the rash looks better. MedlinePlus says finishing all prescribed medicine helps prevent the infection from coming back. StatPearls recommends a repeat swab after treatment to confirm the infection is gone, so ask your doctor whether a follow-up visit is planned.

Do not use leftover antibiotics or swap in antifungal or steroid creams on your own. The AAP also advises against over-the-counter antibiotic ointment for diaper rash, since it can worsen irritation.

How Long It Lasts and Why It Comes Back

With treatment, MedlinePlus says children usually recover quickly, and AAFP says early treatment produces rapid improvement. StatPearls says it usually resolves within 14 to 21 days with proper antibiotic use. Without treatment, AAFP reports symptoms may last three weeks to six months.

Recurrence is common. AAFP reports relapses in up to 39% of cases, and the 2021 review found 19% of children had a recurrence within 6 months, about 90% of them within 3.5 months. AAFP says repeat treatment is usually successful. StatPearls links recurrence to hygiene and habitual behaviors, so the prevention steps below matter.

Rare complications. MedlinePlus lists rare problems such as an abscess, bloodstream infection and kidney inflammation. The 2021 review found that about 11% of reported children developed an immune-related condition afterward, most often guttate psoriasis, a rash of small scaly spots.

Comfort Care at Home While Antibiotics Work

Antibiotics do the healing. These steps add comfort:

• Clean gently with water: the AAP suggests a wet washcloth instead of dry toilet paper for irritated skin. Pat dry rather than rubbing.
• Skip fragrances: the AAP recommends avoiding fragranced children’s products. Packaged wipes can cause a rash in some children.
• Use a barrier for comfort: for irritated skin, the AAP suggests petrolatum ointment or zinc oxide paste. A barrier can protect sore skin from stool, but it does not treat the infection.
• Change diapers promptly: see how to change a diaper.

A sore bottom can disrupt sleep for a few nights. Our guide to baby sleep when sick has tips for getting through rough nights while keeping sleep safe.

Painful Poops, Constipation and Potty Training

Pain with pooping is one of the hallmark symptoms. StatPearls notes that pain with bowel movements can lead to constipation. A child who learns that pooping hurts may start holding it in.

• Ask your pediatrician about fluids and food that keep stools soft while the skin heals.
• Tell your doctor if constipation starts or worsens, and ask before using any stool softener.

Read more in baby constipation and how to help a baby poop. If you see blood, our baby poop color guide explains what different colors can mean, but blood in the stool always deserves a call.

For toddlers in the middle of toilet learning, a painful infection can cause a setback. Pausing until your child is comfortable is fine. See potty training regression and when to start potty training.

Preventing Spread at Home

These habits help prevent reinfection and protect the rest of the family:

• Wash hands well: MedlinePlus says careful handwashing may help prevent this infection. The CDC recommends washing hands often with soap and water. Wash after diaper changes, after toileting help and before eating.
• Do not share cups or utensils: the CDC advises against sharing cups, utensils and bites of food with people who are sick, and recommends washing them after use.
• Keep towels and washcloths separate: StatPearls notes shared items such as bathtubs and toilet seats may play a role in spread, so give your child their own towel and washcloth and clean the tub after baths.
• Check the family: if a sibling or parent has a sore throat or similar symptoms, tell your doctor. Strep throat often spreads within households (CDC).
• Discourage scratching: StatPearls advises breaking the cycle of self-spread, where fingers carry bacteria between the bottom, mouth and nose. Short nails can help.

The sources we reviewed do not set a specific rule for when a child with perianal strep can return to daycare. Ask your pediatrician.

Related Betteroo Guides

• Diaper Rash vs Yeast Infection
• Baby Constipation
• Baby Poop Color Guide
• Teething Rash
• Potty Training Regression
• How to Change a Diaper

When to Call Your Pediatrician

The AAP advises calling if a diaper rash does not clear with home care or gets worse after 2 to 3 days of treatment. Call during office hours if your child has:

• A bright red, sharp-edged rash around the anus: especially with itching or pain.
• Pain with bowel movements: or new or worsening constipation (MedlinePlus).
• Blood in the stool: even streaks.
• A rash that is spreading: to the genitals, thighs or beyond.
• No improvement on antibiotics: MedlinePlus says to contact the provider if your child does not improve soon.
• The rash comes back: after treatment.

Call right away if your child is on antibiotics and the redness gets worse or the pain or fever increases (MedlinePlus), if the rash is very painful (the AAP notes this could mean cellulitis), or if you see pus, oozing, crusty sores or fever along with the rash (AAP).

Call 911 or go to the emergency room if your child is very sleepy or hard to wake, has trouble breathing, or has rapidly spreading redness with severe pain or a high fever.

This article is general education, not medical advice, and does not replace an exam by your child’s doctor.

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