If you are using Isoniazid to treat TB, it should always be used along with another medicine. Isoniazid is an antibacterial. It works by killing TB organisms. Isoniazid also has an antidepressant effect, and it was one of the first antidepressants discovered. Isoniazid can also be used in the treatment of a BCG-oma. Isoniazid only works against TB bacteria; it does not treat viral infections (eg, the common cold).
Use Isoniazid as directed by your doctor. It is important to take Isoniazid regularly to get the most benefit. Take each dose with a full glass (8 ounces) of water. Take Isoniazid on an empty stomach 1 hour before or 2 hours after meals. If nausea occurs, ask your doctor if you can take Isoniazid with food. Take all of the Isoniazid that has been prescribed for you even if you begin to feel better as your symptoms may begin to improve before the infection is completely treated. Your doctor may also want you to take a supplemental vitamin B6 (pyridoxine) tablet daily during treatment to prevent numbness and tingling caused by low levels of this vitamin.
Do not eat foods high in histamine while you use Isoniazid. Eating foods high in histamine (e.g., skipjack, tuna, tropical fish) while you use Isoniazid may cause low blood pressure, irregular heartbeat, headache, sweating, or flushing. Isoniazid may affect your blood sugar. Check blood sugar levels closely. Use Isoniazid with caution in patients older 35 years as they may have a greater risk of severe liver problems from Isoniazid.
Do not use Isoniazid if you are allergic to any ingredient in Isoniazid or have had severe side effects from isoniazid, such as drug fever, chills, or arthritis; if you have severe liver damage, active liver disease, or liver damage from previous use of Isoniazid; if you have a history of hepatitis caused by any medicine; if you have a history of alcohol or other substance abuse, have unsanitary injectable drug habits, or drink alcohol daily; if you are older than 35 years old, you have recently given birth, or you have previously taken Isoniazid.
Possible side effect
The most common side effect is mild stomach upset. Seek medical attention right away if any of these severe side effects occur: severe allergic reactions; changes in vision; chills or fever; dark urine; general feeling of discomfort; increased thirst or urination; joint pain or swelling; loss of appetite; memory problems; mental or mood changes; nausea; seizures; stomach pain or tenderness; symptoms of low vitamin B6 levels (eg, confusion, cracks in the corners of the mouth, irritability, mouth redness or soreness, scaly rash); tingling or numbness in the hands or feet; unusual bruising or bleeding; unusual tiredness or weakness; vomiting; yellowing of the skin or eyes.
Some medicines may interact with Isoniazid. Tell your health care provider if you are taking Acetaminophen, anticoagulants (eg, warfarin), carbamazepine, hydantoins (eg, phenytoin), rifampin, theophylline, or valproic acid because the risk of their side effects may be increased by Isoniazid; Ketoconazole because its effectiveness may be decreased by Isoniazid.
If you miss a dose of Isoniazid, use it as soon as possible. If it is almost time for your next dose, skip the missed dose and go back to your regular dosing schedule. Do not use 2 doses at once.
Seek emergency medical attention if any of these symptoms happen.
Store Isoniazid between 68 and 77 degrees F (20 and 25 degrees C). Brief storage at temperatures between 59 and 86 degrees F (15 and 30 degrees C) is permitted. Store away from heat, moisture, and light. Do not store in the bathroom. Keep Isoniazid out of the reach of children and away from pets.
The information presented at the site has a general character. Note please this information cannot be used for self-treatment and self diagnosis. You should consult with your doctor or health care adviser regarding any specific instructions of your condition. The information is reliable, but we concede it could contain mistakes. We are not responsible for any direct, indirect, special or other damage caused by use of this information on the site and also for consequences of self-treatment.