Just before taking, mix the drug with half a glass (4 ounces or 120 milliliters) of water or milk, or orange, grapefruit, tomato, prune or pineapple juice, and drink all of the mixture. If any of these effects persist or worsen, notify your doctor or pharmacist promptly. Do not increase your dose or use this drug more often or for longer than prescribed. Before taking doxepin, tell your doctor or pharmacist if you are allergic to it; or to other tricyclic antidepressants (such as nortriptyline); or if you have any other allergies. To reduce the risk of dizziness and lightheadedness, get up slowly when rising from a sitting or lying position. Limit your time in the sun. Also, you may experience symptoms such as mood swings, headache, and tiredness.