isoniazid

Take isoniazid on an empty stomach. Food can cause your body to absorb less medication, which might affect how well it works.

To treat active TB infection, you'll need to take isoniazid in combination with other anti-TB antibiotics such as rifampin, pyrazinamide, and ethambutol. And you'll likely need to take this combination for several months.

To prevent TB infection, isoniazid can be taken on its own. And you'll likely need to take it for a few months.

Isoniazid can cause life-threatening liver problems like hepatitis. Avoid drinking alcohol while taking this medication. Let your prescriber know if you have symptoms such as upper belly pain, nausea, vomiting, dark urine, or tiredness.

Since isoniazid can cause nerve problems, your prescriber might recommend that you also take vitamin B6 (pyridoxine) supplements to prevent these side effects.

Isoniazid can change the color of your urine, and some people notice a darker yellow-orange color. This is normal and should go away on its own. But dark urine can also be a sign of serious liver problems, so let your prescriber know if you notice any changes in your urine, especially if you have other symptoms as well.

Avoid foods that contain tyramine (like cheese or red wine) or histamine (like tuna and skipjack), since they can interact with isoniazid and can cause headache, sweating, fast heart rate, flushing, and low blood pressure.

It's very important not to miss any doses of isoniazid or other anti-TB medications. Skipping doses can make the bacteria resistant to the usual antibiotics, which then makes the infection much harder to treat.

In some instances, you might need to take each dose of isoniazid in front of a healthcare professional. This is also known as Directly Observed Therapy (DOT). It can be done in person or virtually. This is important to reduce antibacterial resistance.