Erythromycin: What It Treats and How to Use It Safely

Erythromycin is a macrolide antibiotic you’ll see often for respiratory infections, some skin infections, acne, and certain stomach infections. Doctors choose it when patients are allergic to penicillin or when the bug responds better to a macrolide. It comes as tablets, liquid, topical creams, and an IV formulation for hospital use.

How erythromycin works and common uses

The drug blocks bacterial protein production, which stops bacteria from growing. That makes it useful for bronchitis, whooping cough, some cases of pneumonia, and acne. It’s also used with other drugs to treat Helicobacter pylori in stomach ulcers. At low doses, erythromycin can speed up gut movement—doctors sometimes use it for gastroparesis to help food move through the stomach.

Dosing depends on the infection, age, and form. Liquids are common for children. Extended-release forms are available for adults. Always follow the doctor’s prescription: underdosing can cause treatment failure and encourage resistance; overdosing raises side effect risk.

Side effects, interactions, and safe tips

Expect stomach upset, nausea, and diarrhea—these are the most common complaints. Less common but serious issues include liver inflammation (rare), QT prolongation (affects heart rhythm), and hearing problems in very high doses. If you have severe abdominal pain, yellowing skin, or fainting spells, get medical help.

Erythromycin inhibits CYP3A4, a liver enzyme that breaks down many drugs. That means levels of other medicines can rise when taken together. Watch out for interactions with statins (risk of muscle damage), certain blood thinners like warfarin, some anti-anxiety meds, and drugs that also prolong the QT interval. Grapefruit and grapefruit juice can increase erythromycin levels and should be avoided while taking it.

If you’re pregnant or breastfeeding, tell your doctor. Erythromycin is commonly used in pregnancy, but some forms (the estolate) have been linked to liver problems and are usually avoided. For infants and very young children, dosing and formulation matter—follow pediatric guidance closely.

Practical tips: take pills with food if stomach upset is a problem, but check if your specific form needs an empty stomach. Finish the full course even if you feel better early. Don’t share antibiotics or use leftover pills for a new illness. If you buy medicine online, use a licensed pharmacy, require a prescription, and check customer reviews and verification seals.

If symptoms don’t improve within 48–72 hours or if they worsen, contact your provider. Erythromycin works well for many infections, but correct use and awareness of interactions keep treatment safe and effective.