Isoniazid 100 mg Tablets is indicated for the treatment of tuberculosis caused by Mycobacterium tuberculosis.

a.Do not take Isoniazid 100 mg Tablets
- if you are hypersensitive (allergic) to isoniazid or any of the other ingredients of Isoniazid 100 mg Tablets
- if you have liver disease,
- if you have acute liver disease,
- if you have drug induced liver disease,
- if you have experienced liver damage before when taking isoniazid,
- if you have experienced severe side effects of isoniazid, such as drug fever, chills or inflammation of the joints before.
b.Take special care with Isoniazid 100 mg Tablets
You should promptly report signs or symptoms consistent with liver damage. These include any of the following: unexplained lack of appetite, nausea, vomiting, dark urine, yellowing of the skin and the eye white (jaundice), rash, tingling in the hands and feet, persistent tiredness, weakness lasting longer than 3 days and/or abdominal tenderness, especially in the right upper region of your belly. Your doctor or health care provider will control your liver function regularly.
You may be at special risk for developing hepatitis, if
- you are older than 35 years,
- if you drink alcoholic beverages daily
- if you have a chronic liver disease,
- if you are a user of injection drugs (e.g. heroine).

If you belong to one of these groups your doctor will closely check your liver function.
Furthermore, you will be carefully monitored, if:
- you are taking any long-term medicines,
- you feel numb or weak in your arms or legs or have prickling and tingling sensation on the skin (peripheral neuropathy),
- you are pregnant
- you are HIV infected.
Peripheral neuropathy (tingling in the hands and feet or feeling numb or weak in the arms or legs)) is the most common side effect of isoniazid. If you have kidney problems, you may be at increased risk of experiencing isoniazid side effects.
Vitamin B6 also called pyridoxine should be administered routinely at doses of 10 mg per day during treatment with Isoniazid Tablets, since it largely reduces the risk of developing neuropathy.
If you are hypersensitive (allergic) to ethionamide, pyrazinamide, niacin (nicotinic acid), or other related medications you may also be hypersensitive to this product.
You should inform your doctor if you have diabetes or if you have ever suffered from seizure disorders (fits), psychosis, or liver problems.
It is important that your doctor or health care provider knows about all your symptoms even when you think they are not related to tuberculosis infection.
c.Taking other medicines
Please tell your doctor, health care provider or pharmacist if you are taking or have recently taken any other medicines, including medicines obtained without a prescription. These may affect the action of Isoniazid Tablets, or Isoniazid Tablets may affect their action. Side effects of either medicine may become worse and/or the medicines may become less effective.
You should not take Isoniazid Tablets 100 mg with disulfiram (medicine used for the treatment of alcoholism).
You should Isoniazid Tablets 100 mg at least one hour before taking medicines that contain aluminium hydroxide (used to treat indigestion).
The active agent in Isoniazid Tablets may also interact with the following medicines:
- medicines to treat epileptic seizures (e.g. phenytoin, carbamazepine, valproic acid, phenobarbital)
- medicines used to help you sleep (benzodiazepines, e.g. diazepam, flurazepam, triazolam, midazolam),
- medicines for the treatment of certain psychiatric conditions (neuroleptics, e.g. chlorpromazine, haloperidol),
- medicines for prevention of blood clots (coumarin- or indandione-derivates, e.g. warfarin),
- medicines used prior to surgery (narcotics, e.g. alfentanil, enflurane),
- theophylline (medicine for the treatment of asthma),
- procainamide (medicine for the treatment of cardiac arrhythmias),
- corticosteroids (e.g. prednisolone, medicines for the treatment of inflammations and other diseases, such as asthma or rheumatoid arthritis),
- paracetamol (pain killer),
- medicines toxic to the liver,
- medicines toxic to the nervous system.
d.Taking Isoniazid 100 mg Tablets with food and drink
Isoniazid Tablets should be taken on an empty stomach (at least one hour prior to or two hours after a meal).
If you take Isoniazid Tablets concurrently with cheese or fish, you may experience redness or itching of the skin, hot feeling, rapid or pounding heartbeat, sweating, chills or clammy feeling, headache, or lightheadedness.
Do not drink alcohol while taking Isoniazid Tablets. This increases your risk for liver damage.
e.Pregnancy and breast-feeding
If you become pregnant, or are planning to become pregnant, you must contact your doctor or health care provider to discuss the potential benefits and risks of your tuberculosis therapy for you and your child.
Isoniazid is excreted into the breast milk of lactating mothers. No negative effects have been reported in breast-fed-infants, whose mothers were receiving isoniazid.
However, drug concentrations in breast milk are so low, that you cannot rely upon breast-feeding for adequate tuberculosis prophylaxis or therapy for your child.
f.Driving and using machines
Isoniazid Tablets may cause dizziness and other side effects to the nervous system that can impair your ability to drive and use machines

Always take Isoniazid 100 mg Tablets exactly as your doctor or health care provider told you. You should check with your doctor, health care provider or pharmacist if you are not sure.
The dose of Isoniazid 100 mg Tablets was decided by your doctor based on your body weight.
Active tuberculosis
Daily therapy
Adults:
In adults weighing 30-45 kg the daily dose is two Isoniazid 100 mg Tablets (200 mg), administered as a single dose.
In patients weighing >45 kg the daily dose is three Isoniazid 100 mg Tablets (300 mg), administered as a single dose.
Children: Number of Isoniazid 100 mg tablets by weight band to be taken once daily

Children weighing less than 3.5 kg should not take Isoniazid 100 mg Tablets, as appropriate dose adjustments cannot be made.
Latent tuberculosis
Adults:
The daily dose is three Isoniazid 100 mg Tablets (300 mg) as a single dose for at least 6 months.
Children: Number of Isoniazid 100 mg tablets by weight band to be taken once daily

Swallow Isoniazid 100 mg Tablets whole with water or another drink.
The tablets should be taken on an empty stomach (at least one hour prior to or two hours after a meal).
a.If you take more Isoniazid 100 mg Tablets than you should
If you have taken too many tablets or if someone accidentally swallows some, you may develop nausea, vomiting, lack of appetite, gastrointestinal disturbances, fever, headache, dizziness, slurred speech, hallucinations and/or visual disturbances. Marked isoniazid overdoses lead to respiratory distress and depression of the central nervous system progressing from stupor to come, along with severe seizures. Immediately contact your doctor, health care provider or the nearest hospital emergency department for further advice.
b.If you forget to take Isoniazid 100 mg Tablets
If you miss or forget to take a dose, take the missed dose as soon as possible, unless the next regular dose is scheduled within 6 hours.
Skip the missed dose if it is almost time for your next regular dose.
Do not take a double dose to make up for forgotten individual doses.
c.If you stop taking Isoniazid 100 mg Tablets
Keep taking the medicine for as long as your doctor has told you, even if you are feeling better. If you stop the medicine too soon, your infection may not be completely cured.

You should not stop treatment unless your doctor or health care provider tells you to.
If you have any further questions on the use of this product, ask your doctor or health care provider or pharmacist.

Like all medicines, Isoniazid Tablets can cause side effects, although not everybody gets them. When treating tuberculosis, it is not always possible to differentiate between unwanted effects caused by Isoniazid Tablets or those caused by any other medicines you may be taking at the same time.
For this reason, it is important that you inform your doctor or health care provider of any change in your health.
The following side effects have been reported in patients treated with isoniazid.
The most important adverse effects of isoniazid are nerve injuries and severe and sometimes fatal inflammation of the liver (hepatitis).
The most commonly reported side effects (greater than 1 in every 10 patients treated) are sensations of tingling, pricking, or numbness of the skin, especially in the feet and hands (peripheral neuropathy). Also, increases of liver enzymes as measured in blood samples. Usually, these enzyme increases return to normal within three months despite continued treatment. When the values rise above a certain level your doctor may decide to stop treatment with Isoniazid 100 mg Tablets.
Uncommon side effects (greater than 1 in every 1000 patients treated) are inflammation of the liver (hepatitis), epileptic seizures, inflammation of the brain, personality changes and memory impairment. If you notice sign and symptoms suggestive of liver damage, inform your doctor or health care provider immediately.
The following side effects have been reported in patients treated with isoniazid.
However, frequency estimates for these effects are not available:
- allergic reactions, including skin reactions, such as rash (exanthema, erythema) and/or itching (pruritus), but also severe forms with fever, blisters and involvement of the mucous membranes (e.g. erythema multiforme, Stevens-Johnson syndrome) inflammation of blood vessels (vasculitis), swollen and/or painful lymphnodes (lymphoadenopathy), painful disorder affecting joints, muscles and other soft tissues (rheumatic syndrome, lupus-like syndrome) or life-threatening anaphylactic reactions,
- dizziness, headache, overresponsive reflexes, tremor, vertigo,
- confusion, disorientation, hallucination,

- inflammation of the lungs (pneumonitis),
- build up of acid in the body (metabolic acidosis), increased blood levels of glucose, a vitamin deficiency syndrome called pellagra (with e.g. dementia, loose stools and skin inflammation)
- nausea, vomiting, loss of appetite, dry mouth, flatulence, constipation, abdominal pain
- difficulty in passing urine, kidney damage including kidney inflammation (interstitial nephritis)
- changes in the white blood cell counts (leucopenia, neutropenia, eosinophilia, agranulocytosis), possibly resulting in an increased risk of infection,
- decreased red blood cell counts (anaemia), possibly leading to fatigue, weakness and shortness of breath,
- decreased platelet count, possibly resulting in an increased risk of bruising and bleeding,
- inflammation of the joints (arthritis)
- visual changes due to inflammation of the optic nerve (optic atrophy or neuritis)
If any of the side effects gets serious, or if you notice any side effects not listed in this leaflet, please tell your doctor, health care provider or pharmacist as soon as possible.

Keep out of the reach of children.
Store below 300C in a dry place. Protect from light.

Do not use Isoniazid 100 mg Tablets after the expiry date which is stated on the label and carton. The expiry date refers to the last day of that month.
Medicines should not be disposed of via waste water or household waste. Ask your pharmacist how to dispose of medicines no longer required. These measures will help to protect the environment.