Before you begin using a medication, be sure to inform your doctor of any medical conditions or allergies you may have, any medications you are taking, whether you are pregnant or breast-feeding, and any other significant facts about your health. These factors may affect how you should use this medication.
Birth control: Some antibiotics may decrease the effectiveness of birth control pills. Ask your doctor if you should be using more than one method of birth control while you are taking this medication.
High blood pressure in the brain: Doxycycline may increase the risk of high blood pressure in the brain. This may appear as a bulging soft spot on the head of infants. Contact your doctor right away if you experience blurred vision, double vision, and headache.
Esophagus problems: People taking doxycycline have experienced ulcers and injury to their esophagus. To help prevent this, take doxycycline with a full glass of water while standing or sitting upright. Do not lie down for at least 1 to 2 hours after taking the medication.
Immune system problems: Rarely, people taking medications in the same family as doxycycline may develop symptoms similar to the symptoms of lupus (rash on the cheeks or other body areas; sun sensitivity; joint or muscle pain; fatigue; chest pain; shortness of breath; or swelling of the feet, ankles, or legs). Contact your doctor if you develop these symptoms.
Liver function: People with liver disease may have a higher risk of side effects from this medication. If you have liver disease or reduced liver function, discuss with your doctor how this medication may affect your medical condition, how your medical condition may affect the dosing and effectiveness of this medication, and whether any special monitoring is needed.
Myasthenia gravis: Myasthenia gravis is a condition that causes specific muscle weakness. Doxycycline may make the symptoms of this illness worse. People with myasthenia gravis should discuss with their doctor how this medication may affect their medical condition, how their medical condition may affect the dosing and effectiveness of this medication, and whether any special monitoring is needed.
Other infections: Treatment with any tetracycline may allow normal fungus or types of bacteria not killed by the antibiotic to overgrow, causing unwanted infections such as yeast infections, which may cause vaginal itching and irritation. Women may prevent yeast infections by eating yogurt daily while taking this antibiotic. Talk to your doctor if you have any concerns
Stomach problems: People taking this medication may develop diarrhea caused by an infection with the bacteria C. difficile. If you have loose, watery, and bloody bowel movements, with or without fever or stomach cramps after taking doxycycline, get medical attention as soon as possible. Diarrhea caused by C. difficile infection can lead to serious health problems if it is not properly treated.
Sunburn: An exaggerated sunburn reaction may occur for some people taking tetracyclines, including doxycycline. Avoid exposure to excessive sunlight, including sunlamps and tanning beds, and use sunblock with minimum SPF 15. Stop taking doxycycline at the first sign of skin redness.
Pregnancy: Like other tetracycline antibiotics, doxycycline may cause harm to the developing baby if this medication is taken during pregnancy. This medication should not be used during pregnancy unless the benefits outweigh the risks. If you become pregnant while taking this medication, contact your doctor immediately.
Breast-feeding: This medication passes into breast milk and causes discolouration of the teeth and reduced bone growth in a breast-feeding infant if it is taken by the mother while still breast-feeding. Due to the adverse effects on the developing infant, this medication should not be used by women who are breast-feeding.
Children: The use of doxycycline during tooth development (from the last trimester of pregnancy to the age of 8 years) may cause permanent discoloration of the teeth (yellow-grey-brown). Though more commonly associated with long-term use of tetracyclines, this effect has also been known to occur after taking the medication for a short time.
The safety and effectiveness of using this medication have not been established for children under 8 years of age.