Erythromycin – Uses, Dosing, Side Effects

Erythromycin is a macrolide antibiotic you’ll see for respiratory infections, skin infections, some sexually transmitted infections, and sometimes to help gut motility. It’s been around for decades, so doctors know its strengths and where it can cause trouble. This page gives straightforward advice on how people usually take it, what to watch for, and simple safety tips.

How people use erythromycin

For common infections, adults often take 250–500 mg every 6 to 12 hours depending on the product and the bug being treated. Kids are dosed by weight—typical ranges are 30–50 mg/kg per day split across doses. There are several forms: tablets, capsules, and liquid suspensions. Some hospitals use IV erythromycin for serious infections.

Tip: erythromycin absorbs better on an empty stomach, so take it 1 hour before or 2 hours after meals. If it upsets your stomach, taking it with food is fine—comfort matters so you finish the full course.

Off-label use: low doses of erythromycin can be used as a prokinetic (to speed stomach emptying) in gastroparesis. That’s a different dosing plan and should be managed by a doctor.

Side effects, interactions, and safety

The most common side effects are stomach upset, nausea, abdominal cramps, and diarrhea. If you get severe watery diarrhea or fever after antibiotics, call your doctor—Clostridioides difficile infection is a rare but serious risk.

Erythromycin affects the heart rhythm in some people. It can lengthen the QT interval, so avoid combining it with other QT‑prolonging drugs (for example, some antipsychotics, certain antiarrhythmics like amiodarone) without medical advice. Tell your prescriber if you have heart disease, low potassium, or low magnesium.

Drug interactions are common. Erythromycin can raise levels of drugs metabolized by CYP3A4. Watch especially for: simvastatin (risk of muscle damage), warfarin (may increase bleeding—monitor INR), and certain benzodiazepines and antiarrhythmics. Always tell your pharmacist every medicine and supplement you take.

Rare but serious: allergic reactions or liver problems (jaundice, dark urine). If you notice rash, swelling, yellow skin, or severe abdominal pain, get medical help right away.

Practical tips: finish the full course unless your doctor tells you to stop. Don’t share antibiotics or use leftover pills. If you’re pregnant, breastfeeding, or have liver disease, discuss risks and alternatives with your provider. If you buy medication online, use a licensed pharmacy and a valid prescription.

If something feels off—new rash, heart palpitations, fainting, or severe diarrhea—call your healthcare provider. For simple questions like how to take it with other meds or what to do if you miss a dose, your pharmacist is a good first stop.