Dapsone — what it treats, what to watch for, and how to stay safe

Dapsone is an older drug that still does a lot of useful work. It has both antibacterial and anti-inflammatory effects, so doctors use it for a few skin diseases and as an alternative when common antibiotics aren’t an option. If someone mentions dapsone, the main things to know are what it treats, the most serious side effects, and simple steps to use it safely.

How people use dapsone

Here are the common uses you’ll see in real-life care:

• Leprosy: Dapsone is a core part of multi-drug therapy for Hansen’s disease (leprosy).
• Dermatitis herpetiformis: This itchy blistering rash often responds quickly to dapsone and is one of its best-known uses.
• Acne and rosacea: There’s a topical dapsone gel (usually 5%) used for inflammatory acne and some rosacea cases; oral dapsone is sometimes used for severe, treatment-resistant acne.
• Pneumocystis jirovecii pneumonia (PCP) prevention: When patients can’t take trimethoprim‑sulfamethoxazole, dapsone can be an alternative for prophylaxis in certain situations.
• Other skin conditions: Doctors sometimes use dapsone for autoimmune blistering diseases and other neutrophil-driven skin problems.

Side effects to watch and basic monitoring

Two side effects come up most often and deserve attention. First, dapsone can cause hemolytic anemia — that’s when red blood cells break down faster than they should. This risk is much higher if a person has G6PD deficiency, so testing for G6PD before starting dapsone is standard practice.

Second, dapsone can cause methemoglobinemia, a condition where hemoglobin can’t carry oxygen normally. Symptoms include shortness of breath, tiredness, bluish skin or lips, and dark urine. If these appear, call a doctor right away.

Other problems include a rare but serious hypersensitivity reaction (fever, rash, liver problems—sometimes called DRESS), peripheral neuropathy (numbness or tingling), and liver test abnormalities. For safety, providers usually check a baseline complete blood count (CBC), liver tests, and G6PD level, then repeat CBCs during treatment.

Practical tips: always tell your provider about other medicines you take because some drugs can change dapsone levels. If you have known G6PD deficiency, dapsone is generally avoided. If you’re pregnant or breastfeeding, discuss risks and alternatives with your clinician — dapsone crosses the placenta and can affect the baby in rare cases.

Quick takeaway: dapsone works well for certain skin diseases and as an alternative in specific infections, but it needs simple checks before and during use. Ask your clinician about G6PD testing, regular blood work, and what signs should prompt urgent care. If you want more on skin meds, antibiotics, or safe prescribing, check related guides on this site or ask your pharmacist for a plain explanation.