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Isoniazid

About your medicine

Isoniazid is a drug which may be taken after a kidney transplant by patients who may come into contact with or have previously had tuberculosis (TB) - a long term infection which mainly affects the lungs, but which can affect any part of your body. It is given at a low dose to prevent TB infections.

Taking your medicine

Before taking your medicine read the information leaflet inside the pack. It will give you more information about the medicine including a full list of the side effects.

You should swallow the tablets whole with a glass of water, take them exactly as recommended by the doctor. It is best to take the tablets half an hour before food or two hours after. This is because isoniazid is absorbed better when your stomach is empty.

Unwanted effects

As with all medicines, isoniazid can cause side effects in some people. The most common side effects include feeling sick and being sick.You should tell your doctor if you suffer badly with being sick. It may also damage peripheral nerves which can cause tingling or a loss of feeling in your hands and feet. This can be avoided by taking another tablet called pyridoxine once a day. This is a vitamin which should be taken every day while you are taking isoniazid.

Other side effects can include liver problems. Your doctor will arrange for you to have blood tests while you are taking isoniazid to ensure your liver is working properly.

Unwanted effects often improve after a short while however if they are prolonged or troublesome speak with your doctor or pharmacist.

Storing your medicine

You should store the tablets in their original packet in a cool, dry place out of the sight and reach of children.

Do not throw out any expired or unwanted medicine by flushing them down the toilet or throwing them away. Take them to your local pharmacy which will dispose of them for you.

Other advice

Always take your tablets as directed by your doctor and only stop them on the advice of your doctor.

Some drugs may cause a problem when taken with isoniazid. These include some anti-epileptic drugs and theophylline. This is not a full list so always check with your doctor or pharmacist before taking any other medication along with isoniazid including medicines that you can buy without a prescription or any herbal and complimentary medicines.


The National Kidney Federation cannot accept responsibility for information provided. The above is for guidance only. Patients are advised to seek further information from their own doctor.

NKF Controlled Document No. 67: Isoniazid written: 22/04/2000 last reviewed: 01/10/2016