Take this medication by mouth on an empty stomach (at least 1 hour before or 2 hours after a meal) as directed by your doctor, usually 2 to 4 times a day. 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 drug. For this reason, do not take it right before bedtime.

If stomach upset occurs, ask your doctor if you can take this medication with food.

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 demeclocycline, preventing your body from fully absorbing the drug.

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

If you are taking this medication to treat an infection, continue to take it 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. If you are using this medication to treat SIADH, you should notice an increase in the amount of urine within 5 days.