Azithromycin Side Effects: What to Watch For

If you’ve been prescribed azithromycin (brand name Zithromax), you probably expect it to clear your infection fast. Most people finish the course without a hitch, but a few notice unwanted reactions. Knowing the most likely side effects lets you stay ahead, notice when something’s off, and decide when to call your doctor.

Common side effects you might feel

Azithromycin is an antibiotic, so it can stir up your stomach and gut. The most frequent complaints are:

• Upset stomach, nausea, or mild vomiting
• Diarrhea, sometimes a bit watery
• Headache or light‑headed feeling
• Feeling a bit tired or weak

These usually start within a day or two of taking the pill and fade when you finish the course. Drinking plenty of water and eating a light snack can soften the stomach upset.

When to seek medical help

Most side effects are harmless, but a few signal a bigger problem. Call your doctor right away if you notice:

• Severe rash, itching, or swelling, especially around the face or throat
• Difficulty breathing or wheezing
• Rapid heartbeat, dizziness that won’t go away, or fainting
• Persistent, bloody, or black‑tarry diarrhea (could mean a serious gut infection)
• Heart palpitations or a feeling that your heart is racing

These signs may point to an allergic reaction or a rare but serious condition called QT‑prolongation, which affects the heart’s rhythm.

Kids, older adults, and people with liver disease, kidney problems, or a history of heart rhythm issues are more likely to feel stronger side effects. Tell your doctor about any other medicines you’re taking—especially other antibiotics, antacids, or heart drugs—because azithromycin can interact and boost side‑effect risk.

If you miss a dose, take it as soon as you remember unless it’s almost time for the next one. Don’t double up; an extra pill won’t speed healing and could increase stomach trouble.

Bottom line: most people handle azithromycin just fine, but keeping an eye on your body helps you catch problems early. Stay hydrated, eat light, and reach out to your healthcare provider if anything feels out of the ordinary. Your health is worth the quick check‑in.