It is very important that your doctor check your progress at regular visits. Also, check with your doctor immediately if blurred vision or loss of vision, with or without eye pain, occurs during treatment. Your doctor 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.
Certain foods such as cheese (Swiss or Cheshire) or fish (tuna, skipjack, or Sardinella) may rarely cause reactions in some patients taking isoniazid. 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 while you are taking this medicine.
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.
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, check with your doctor immediately. These may be early warning signs of more serious liver or nerve problems that could develop later.
- For diabetic patients:
- This medicine may cause false test results with some urine sugar tests. Check with your doctor before changing your diet or the dosage of your diabetes medicine.