If your symptoms do not improve within a few days, or if they become worse, check with your doctor.
Using this medicine while you are pregnant can harm your unborn baby. Use an effective form of birth control to keep from getting pregnant. If you think you have become pregnant while using this medicine, tell your doctor right away.
This medicine may darken the color of your skin, nails, eyes, teeth, gums, or scars. Talk with your doctor if you have any concerns.
Doxycycline may cause diarrhea, and in some cases it can be severe. It may occur 2 months or more after you stop taking this medicine. Do not take any medicine to treat diarrhea without first checking with your doctor. Diarrhea medicines may make the diarrhea worse or make it last longer. If you have any questions about this or if mild diarrhea continues or gets worse, check with your doctor.
Birth control pills (containing estrogen) may not work properly while you are using doxycycline. To keep from getting pregnant, use other forms of birth control. These include condoms, a diaphragm, or a contraceptive foam or jelly.
Doxycycline may cause your skin to be more sensitive to sunlight than it is normally. Exposure to sunlight, even for short periods of time, may cause skin rash, itching, redness or other discoloration of the skin, or a severe sunburn. When you begin taking this medicine:
Stay out of direct sunlight, especially between the hours of 10:00 a.m. and 3:00 p.m., if possible.
Wear protective clothing, including a hat. Also, wear sunglasses.
Apply a sunblock product that has a sun protection factor (SPF) number of at least 15. Some patients may require a product with a higher SPF number, especially if they have a fair complexion. If you have any questions about this, check with your doctor.
Apply a sunblock lipstick that has an SPF of at least 15 to protect your lips.
Do not use a sun lamp or tanning bed or booth.
If you have a severe reaction from the sun, check with your doctor.
Serious skin reactions, including drug reaction with eosinophilia and systemic symptoms can occur with this medicine. Check with your doctor right away if you have blistering, peeling, or loosening of the skin, red skin lesions, severe acne or a skin rash, sores or ulcers on the skin, fever or chills, cough, sore throat, swollen, painful, or tender lymph glands in the neck, armpit, or groin, or yellow skin or eyes while using this medicine.
This medicine may cause increased pressure inside the head (intracranial hypertension). This is more likely to occur in women of childbearing age who are overweight or have a history of intracranial hypertension. Tell your doctor right away if you have a headache, blurred vision, or changes in vision.
Contact your doctor immediately if fever, rash, joint pain, or tiredness occurs. These could be symptoms of an autoimmune syndrome where the body attacks itself.
You should not take antacids that contain aluminum, calcium or magnesium, or any product that contains iron, such as vitamin or mineral supplements.
If you are using this medicine to prevent malaria, take extra care not to get bitten by mosquitoes. Use protective clothing, mosquito netting or screens, and an insect repellent.
Before you have any medical tests, tell the medical doctor in charge that you are taking this medicine. The results of some tests may be affected by this medicine.
Do not take other medicines unless they have been discussed with your doctor. This includes prescription or nonprescription (over-the-counter [OTC]) medicines and herbal or vitamin supplements.