Benzamycin Side Effects: What to Expect and When to Call Your Doctor

Benzamycin (erythromycin 3%/benzoyl peroxide 5% topical gel) is generally well tolerated, but like any prescription medication, it can cause side effects. Most are mild and improve as your skin adjusts. A small number of side effects are more serious and warrant prompt medical attention. This guide walks you through what to expect — from the very common to the rare but important.

How Common Are Benzamycin Side Effects?

In controlled clinical trials, the incidence of adverse reactions associated with Benzamycin Topical Gel was approximately 3%. This is relatively low compared to many acne treatments. The most frequently reported reactions were dryness and urticarial (hive-like) reactions. Additional reactions were reported occasionally but are not uncommon in clinical practice.

Common Side Effects (Usually Mild and Temporary)

These side effects are most common in the first 2–4 weeks of treatment and tend to improve as your skin adjusts:

• Dryness: The most commonly reported side effect. Benzoyl peroxide reduces skin oiliness, which can lead to dryness or flaking, especially if your skin tends to be dry already.
• Redness (erythema): Mild skin redness, particularly in the area where the gel is applied, is common when starting treatment.
• Peeling: Benzoyl peroxide has a keratolytic effect that speeds up skin cell turnover, which can cause flaking or peeling, especially in the first few weeks.
• Itching: Mild itching at the application site is occasionally reported. If itching is severe or persistent, contact your doctor.
• Burning or stinging: A mild burning or stinging sensation on application is commonly reported in the first weeks.
• Oiliness or tenderness: Some patients report changes in skin texture or tenderness in treated areas.

The Bleaching Effect: What You Need to Know

One of the most practical concerns with Benzamycin is that the benzoyl peroxide component

can bleach hair and colored fabric. This includes pillowcases, towels, clothing, and eyebrows. To minimize bleaching:

• Allow the gel to fully dry before contact with fabric
• Use white or light-colored pillowcases and towels
• Avoid touching colored clothing immediately after application

Serious Side Effects: When to Call Your Doctor

Serious side effects from Benzamycin are uncommon but can occur. Contact your doctor or seek immediate care if you experience:

• Signs of an allergic reaction: Hives, swelling of the face or throat, shortness of breath, or difficulty swallowing. Seek emergency care immediately.
• Severe skin irritation: If your skin becomes very red, swollen, blistered, or painful, stop using Benzamycin and call your doctor.
• Diarrhea or bloody stool: Benzamycin contains erythromycin (a topical antibiotic). In rare cases, topical antibiotics can cause Clostridioides difficile (C. diff) infection, resulting in severe diarrhea. This can occur during treatment or up to 2 months after stopping. Contact your doctor immediately if you develop persistent diarrhea.
• Eye, nose, or mouth irritation: If Benzamycin contacts the eyes or mucous membranes, rinse thoroughly with water and contact your doctor if irritation persists.

How to Reduce Side Effects from Benzamycin

Several strategies can minimize common side effects while you adjust to Benzamycin:

• Use a gentle, non-comedogenic moisturizer to counteract dryness
• Wash your face with a mild, fragrance-free cleanser (not harsh scrubs) before applying
• Apply only a thin, pea-sized amount to the affected area — using more doesn't improve results and increases irritation
• Avoid other potentially irritating products on treated areas (harsh toners, other acne treatments, scrubs)
• Limit sun exposure and use a broad-spectrum SPF 30+ sunscreen daily, as benzoyl peroxide can increase sun sensitivity

For information on medications and products that can interact with Benzamycin, see our guide to Benzamycin drug interactions.

If you're having trouble locating Benzamycin at your pharmacy, medfinder.com can help you find it in stock near you.