Precautions to take during treatment with doxycycline include avoiding pregnancy due to potential harm to the fetus; using nonhormonal birth control because hormonal methods may not work properly; avoidance of antacids that contain aluminum, calcium or magnesium; avoidance of vitamins that contain iron; and protecting the skin from direct sunlight, according to Mayo Clinic. While on doxycycline, it is important to avoid taking prescription or over-the-counter medicines or supplements without first discussing it with a doctor.
Doxycycline can affect the results of some medical tests; therefore, the patient should inform the treating physician of its use prior to undergoing any tests or labs, warns Mayo Clinic. The patient should contact his physician if he experiences symptoms such as fever, rash, joint pain or fatigue, as these could be symptomatic of an autoimmune reaction to the medication. Other symptoms of concern include headache, blurred vision or vision changes, which may indicate intracranial hypertension. Diarrhea frequently occurs with this medication, but over-the-counter diarrhea medicine may worsen or prolong the diarrhea.
Doxycycline can cause an increased sensitivity to sunlight, resulting in skin rash, itching, discoloration or severe sunburn, notes Mayo Clinic. The medication may also cause darkening of the eyes, teeth, skin, nails or gums. The patient should discuss any concerning or worsening symptoms with his doctor.