Antibiotics: what they treat, how to use them, and how to stay safe

Antibiotics save lives, but they’re not magic. Use them only for bacterial infections, follow your prescriber, and watch for side effects. Misuse drives antibiotic resistance — that’s a real threat that makes simple infections harder to treat.

Common antibiotic types and what they do

Here are the names you'll see most often and what they usually treat:

- Penicillins (amoxicillin, ampicillin): often used for ear infections, strep throat, and some lung infections.
- Cephalosporins (cephalexin, cefuroxime): a broader group used for skin, urinary tract, and respiratory infections.
- Macrolides (azithromycin, clarithromycin): used when patients are allergic to penicillin or for atypical pneumonia.
- Tetracyclines (doxycycline): used for acne, some respiratory infections, and tick-borne illnesses.
- Nitroimidazoles (metronidazole, tinidazole): used for certain gut or vaginal bacterial infections and some dental infections.
- Fluoroquinolones (ciprofloxacin, levofloxacin): strong options for complicated UTIs and some severe infections, but carry higher risk of tendon and nerve side effects and should be used carefully.

Which antibiotic is right depends on the infection, your allergies, other medicines you take, and local resistance patterns. Your prescriber will pick the best one.

How to use antibiotics safely

Follow these simple rules so antibiotics work and stay effective for everyone:

- Take exactly as prescribed. Don’t skip doses or stop early without talking to your prescriber. Missing doses can let bacteria survive and become resistant.
- Tell your provider about allergies and all medicines you take — some antibiotics interact with blood thinners and other drugs.
- Watch for common side effects like stomach upset, diarrhea, and yeast infections. If you get a rash, swelling, severe diarrhea, or breathing problems, seek medical help right away.
- Avoid alcohol with metronidazole and tinidazole — it can cause bad reactions.
- Don’t use leftover antibiotics or someone else’s prescription. The dose and duration might not fit your infection.

Sometimes doctors start treatment before test results return. If a culture later shows a different bug, they may switch antibiotics. That’s normal and helps target the infection better.

If you’re worried about resistance or want alternatives, ask your prescriber. For example, tinidazole or clindamycin may replace metronidazole in some cases, while doxycycline can be an alternative for certain skin or respiratory infections. Never swap antibiotics on your own.

Buying antibiotics online? Use licensed pharmacies, require a valid prescription, check for clear contact info and verified reviews, and avoid suspiciously cheap offers with no prescription required. If something feels off, walk away.

If you have specific symptoms or a chronic condition, talk to a clinician. Antibiotics can be powerful tools when used correctly — smart use keeps them working for everyone.