What to Know About Zelsuvmi Side Effects

Zelsuvmi (berdazimer topical gel, 10.3%) is the first FDA-approved at-home treatment for molluscum contagiosum. Like all medications, it can cause side effects — but most are mild and happen right where you apply the gel.

Understanding what's normal and what's not can help you feel more confident using Zelsuvmi. This guide covers the most common side effects, how to manage them, and the warning signs that mean you should call your doctor.

How Zelsuvmi Works (And Why Side Effects Happen)

Zelsuvmi works by releasing nitric oxide directly onto molluscum lesions. Nitric oxide has antiviral properties — it blocks viral proteins, damages viral DNA, and stops the molluscum contagiosum virus from replicating. To learn more about the science, read our guide on how Zelsuvmi works.

Because the gel is applied directly to the skin, most side effects are local skin reactions at the application site. These reactions are actually a sign that the medication is interacting with your skin and the virus beneath it.

Common Side Effects

In clinical trials, the following side effects were reported by patients using Zelsuvmi:

Managing Common Side Effects

Pain, Burning, or Stinging (19%)

This is the most frequently reported side effect. It typically happens right after applying the gel and usually subsides within minutes to an hour.

What you can do:

• Apply the gel gently — don't rub it in aggressively
• Let the gel dry completely (about 10 minutes) before covering with clothing
• A cool, damp cloth held near (not on) the treated area may help
• If pain is severe, talk to your doctor about adjusting how much gel you apply

Redness (12%)

Some redness around the treated bumps is common and usually mild. It often fades within a few hours after application.

What you can do:

• Avoid rubbing or scratching the area
• Don't apply other topical products (lotions, creams) directly on top of Zelsuvmi
• If redness spreads beyond the treated area or gets worse over days, contact your doctor

Itching (6%)

Mild itching at the application site is common. This usually goes away on its own.

What you can do:

• Avoid scratching — this can irritate the skin further and spread molluscum
• Keep nails trimmed (especially for children)
• Ask your doctor about using an over-the-counter antihistamine if itching is bothersome

Skin Peeling (5%)

Some peeling or flaking of the skin around treated lesions can occur. This is often part of the healing process.

What you can do:

• Don't pick at peeling skin
• Keep the area clean and dry
• Moisturize the surrounding (untreated) skin if needed

Fever (2%)

A low-grade fever was reported in a small number of patients, mainly in pediatric clinical trials.

What you can do:

• Monitor the temperature
• Use age-appropriate fever reducers (acetaminophen or ibuprofen) if needed
• Contact your doctor if the fever is above 102°F (38.9°C) or lasts more than 2 days

Serious Side Effects (Rare)

Serious side effects from Zelsuvmi are uncommon, but they can happen. Contact your doctor right away if you experience:

• Severe allergic skin reactions — Intense redness, swelling, blistering, or hives at or beyond the application site
• Skin erosion — Breakdown of the outer skin layer at the treatment site, which may look like an open sore or raw skin
• Signs of infection — Increased warmth, pus, spreading redness, or worsening pain at the application site

When to Call Your Doctor

Call your doctor or seek medical attention if:

• Side effects are severe or getting worse over time rather than improving
• You see signs of an allergic reaction — hives, difficulty breathing, or swelling of the face, lips, or throat
• The skin at the application site breaks open, oozes, or becomes infected
• Your child develops a high fever (above 102°F) after starting treatment
• You're unsure whether a reaction is normal

When in doubt, call. Your doctor would rather hear from you early than deal with a problem that got worse.

Side Effects in Children vs. Adults

Zelsuvmi is approved for patients 1 year of age and older. In clinical trials, side effects in children were similar to those in adults, with application site reactions being the most common.

A few things to keep in mind for pediatric patients:

• Children may be more vocal about stinging or burning — this is normal and usually brief
• Fever was slightly more common in children
• Younger children may need help with application to avoid getting gel in their eyes or mouth
• Watch for scratching — kids may scratch treated areas, which can spread molluscum

Tips to Reduce Side Effects

• Follow the mixing instructions exactly. Use the dosing guide to mix equal amounts (0.5 mL each) from Tube A and Tube B for about 20 seconds before applying. Read our full dosage and usage guide for details.
• Apply a thin, even layer. More gel doesn't mean better results — it just means more irritation.
• Let it dry for 10 minutes. Don't cover the area or put on tight clothing until the gel is dry.
• Avoid water for 1 hour. Don't swim, bathe, or wash the treated area for at least an hour after application.
• Wash your hands after applying (unless your hands are being treated).
• Don't mix with other topicals. Avoid applying other creams, lotions, or treatments to the same area without asking your doctor about potential interactions.

How Long Do Side Effects Last?

Most common side effects are temporary — they occur shortly after application and resolve within hours. As your skin adjusts to the medication over the first week or two, side effects often become less noticeable.

Zelsuvmi is used once daily for up to 12 weeks. If side effects persist or worsen after the first two weeks, talk to your doctor. They may adjust your treatment plan.

The Bottom Line

Zelsuvmi's most common side effects — stinging, redness, and itching — are typical of topical skin treatments and usually mild. Serious side effects are rare. The key is knowing what to expect so you can use the medication confidently and know when to reach out for help.

If you're still deciding whether Zelsuvmi is right for you, check out our guides on what Zelsuvmi is and how to save money on it. And if you're ready to fill your prescription, learn how to check if a pharmacy has Zelsuvmi in stock.