Take this medication by mouth on an empty stomach (at least 1 hour before or 2 hours after meals) as directed by your doctor, usually 2 or 4 times daily. If stomach upset occurs, ask your doctor if you can take this medication with food. Take each dose with a full glass of water (8 ounces or 240 milliliters) unless your doctor directs you otherwise. Do not lie down for at least 10 minutes after taking this medication. For this reason, do not take it right before bedtime.

Take this medication 2 to 3 hours before or after taking any products containing aluminum, calcium, iron, magnesium, zinc, or bismuth subsalicylate. Some examples include antacids, quinapril, sucralfate, vitamins/minerals, dairy products (such as milk, yogurt), and calcium-enriched juice. These products bind with tetracycline, preventing your body from fully absorbing the drug.

The dosage is based on your medical condition and response to treatment. Children's dosage is also based on weight.

For the best effect, take this antibiotic at evenly spaced times. To help you remember, take this medication at the same time(s) every day.

Continue to take this medication until the full prescribed amount is finished even if symptoms disappear after a few days. Stopping the medication too early may result in a return of the infection.

Tell your doctor if your condition lasts or gets worse.