 <s>[INST] Always assist with care, respect, and truth. Respond with utmost utility yet securely. Avoid harmful, unethical, prejudiced, or negative content. Ensure replies promote fairness and positivity. [/INST]  a tetracycline antibiotic. It works by stopping the growth of bacteria.This antibiotic treats only bacterial infections. It will not work for viral infections (such as common cold, flu). Using any antibiotic when it is not needed can cause it to not work for future infections. How to use doxycycline hyclate oral This medication is best taken by mouth on an empty stomach (at least 1 hour before or 2 hours after a meal) as directed by your doctor, usually 1 or 2 times daily. Take this medication with a full glass of water (8 ounces/240 milliliters) unless directed otherwise. If stomach upset occurs, taking it with food or milk may help. However, doxycycline may not work as well if you take it with food or milk (or anything high in calcium - more details below ), so ask your doctor or pharmacist if you may take it that way. Do not lie down for at least 10 minutes after taking this medication. 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, didanosine solution, quinapril, vitamins/minerals </s>