It is very important that your doctor check your progress at regular visits. In addition, you should check with your doctor immediately if blurred vision or loss of vision, with or without eye pain, occurs during treatment. He or she may want you to have your eyes checked by an ophthalmologist (eye doctor).
If your symptoms do not improve within 2 to 3 weeks, or if they become worse, check with your doctor.
Oral contraceptives (birth control pills) containing estrogen may not work properly if you take them while you are taking rifampin and isoniazid combination. Unplanned pregnancies may occur. You should use a different means of birth control while you are taking this medicine. If you have any questions about this, check with your health care professional.
Liver problems may be more likely to occur if you drink alcoholic beverages regularly while you are taking this medicine. Also, the regular use of alcohol may keep this medicine from working properly. Therefore, you should strictly limit the amount of alcoholic beverages you drink while you are taking this medicine.
Certain foods such as cheese (Swiss or Cheshire) or fish (tuna, skipjack, or Sardinella) may rarely cause reactions in some patients taking isoniazid-containing medicines. Check with your doctor if redness or itching of the skin, hot feeling, fast or pounding heartbeat, sweating, chills or clammy feeling, headache, or lightheadedness occurs after eating these foods while you are taking this medicine.
This medicine will cause the urine, stool, saliva, sputum, sweat, and tears to turn reddish-orange to reddish-brown. This is to be expected while you are taking this medicine. This effect may cause soft contact lenses to become permanently discolored. Standard cleaning solutions may not take out all the discoloration. Therefore, it is best not to wear soft contact lenses while taking this medicine. This condition will return to normal once you stop taking this medicine. Hard contact lenses are not discolored by this medicine. If you have any questions about this, check with your doctor.
If this medicine causes you to feel very tired or very weak; or causes clumsiness; unsteadiness; a loss of appetite; nausea; numbness, tingling, burning, or pain in the hands and feet; or vomiting, stop taking it and check with your doctor immediately. These may be early warning symptoms of more serious liver or nerve problems that could develop later.
Rifampin and isoniazid combination may cause blood problems. These problems may result in a greater chance of certain infections, slow healing, and bleeding of the gums. Therefore, you should be careful when using regular toothbrushes, dental floss, and toothpicks. Dental work should be delayed until your blood counts have returned to normal. Check with your medical doctor or dentist if you have any questions about proper oral hygiene (mouth care) during treatment.