Doxycycline: What It Treats and How to Use It Safely

Doxycycline is a widely used antibiotic that treats everything from acne and respiratory infections to Lyme disease and malaria prevention. It's popular because it's effective, available in low cost, and taken by mouth. But a few simple rules make it work better and keep you safer.

First, remember this: finish the whole course even if you feel better. Stopping early can let bacteria survive and become resistant. Also, doxycycline won't help colds or flu — those are viruses, not bacteria.

Common Uses and Typical Dosing

Doctors prescribe doxycycline for skin infections (acne), sinus and lung infections, urinary tract infections, Lyme disease, chlamydia, and as malaria prevention for travelers. Typical adult dosing for most infections is 100 mg twice a day. For malaria prevention, many regimens use 100 mg once daily starting 1–2 days before travel and continuing for 4 weeks after leaving the area. For acne, lower daily doses (40–100 mg) are common. Always follow your prescriber — doses vary by infection.

Side Effects, Interactions, and Practical Tips

Common side effects are nausea, diarrhea, and increased sensitivity to sunlight. Wear sunscreen and avoid long sun exposure because doxycycline can cause bad sunburns. If you get severe diarrhea or bloody stool, call your doctor right away — that could be C. difficile.

Avoid taking doxycycline with antacids, iron, calcium supplements, or milk within 2–3 hours. These bind the drug and lower its effect. Take it with a full glass of water and stay upright for 30 minutes to prevent throat or esophagus irritation. If it upsets your stomach, you can take it with food, but skip dairy close to the dose.

Important drug interactions: doxycycline can increase bleeding if you take warfarin. It may also affect the reliability of some hormonal birth control — consider a backup method while you’re on antibiotics. Tell your doctor about all medicines and supplements you use.

Pregnancy and young children: Doxycycline is generally avoided during pregnancy and in children under 8 because it can affect bone and tooth development. If you are pregnant or breastfeeding, speak to your provider for safer alternatives.

Storage is simple: keep pills at room temperature away from heat and direct light. Don’t use outdated medication.

When to call your doctor: severe allergic reaction (hives, swelling, trouble breathing), high fever, severe diarrhea, yellowing skin or eyes, or sudden vision changes or intense headaches. Any worrying symptom after starting doxycycline deserves a prompt call.

Doxycycline is a helpful, flexible antibiotic when used right. Follow dosing instructions, avoid interacting substances, protect your skin from the sun, and finish the course. If anything feels off, check with your healthcare provider — quick action prevents small problems from getting worse.