Doxycycline Dosage: What You Need to Know

If you’ve been prescribed doxycycline, you probably wonder how much to take and when. Doxycycline is an antibiotic that works for many infections, acne, and even malaria prevention. Getting the dose right helps the medicine work fast and cuts down on side effects.

Standard Adult Doses

For most infections, doctors order 100 mg once or twice a day. The exact amount depends on the bug you’re fighting. For acne, the usual plan is 50‑100 mg daily, often taken with food to avoid stomach upset. When you’re using doxycycline for malaria prevention, the common schedule is 100 mg a day, starting a few days before travel and continuing until a day after you leave the risky area.

How to Take It Correctly

Take doxycycline with a full glass of water. Staying upright for at least 30 minutes stops the pill from irritating your throat. Food can help with nausea, but avoid dairy, calcium supplements, or antacids at the same time—they can lower how much medicine your body absorbs.

When you need to split the dose, use the tablet cutter that comes with the prescription. Chewing or crushing the tablet isn’t a good idea because it can irritate your mouth and stomach.

Kids get a weight‑based dose, usually 2.2 mg per kilogram of body weight each day, divided into two doses. Ask your pharmacist for a pediatric formulation if you’re treating a child.

If you miss a dose, take it as soon as you remember—unless it’s almost time for the next dose. In that case, skip the missed one and keep your regular schedule. Never double‑up; too much doxycycline can cause stomach pain and increase the risk of sun sensitivity.

Sun sensitivity is a well‑known side effect. Wear sunscreen, a hat, and long sleeves when you’re out in the sun, especially if you’re on the drug for acne or long‑term use.

Common side effects include nausea, diarrhea, and a mild yeast infection in the mouth or vagina. If these get worse or you notice a rash, fever, or severe stomach cramps, call your doctor right away. Those could be signs of a more serious reaction.

Most people finish a doxycycline course in 7‑14 days. Some infections, like Lyme disease, may need a longer course—up to 21 days. Always finish the entire prescription, even if you feel better early. Stopping early can let the bacteria grow back and become resistant.

In summary, the typical adult dose is 100 mg once or twice daily, adjusted for the condition you’re treating. Take it with water, avoid calcium at the same time, protect your skin from the sun, and finish the full course. If you have any confusion about timing or side effects, your pharmacist is a great resource for quick answers.