Isoniazida para tuberculose
Revisado por Sid DajaniÚltima atualização por Michael Stewart, MRPharmSÚltima atualização 4 Jul 2023
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Isoniazid is one of several medicines that you will need to take to treat tuberculosis (TB).
It is important that you take the tablets regularly every day.
The ideal time to take the tablets is half an hour before breakfast.
Em resumo
Isoniazid is a medicine used to treat tuberculosis (TB).
It is usually taken as a tablet, often combined with other TB medicines.
Take your tablets each day, ideally half an hour before breakfast.
You will need regular blood tests to check your liver while taking this medicine.
Speak to your doctor if you experience tingling, muscle weakness or yellow skin.
About isoniazid
Tipo de medicamento | Um medicamento antituberculose |
Usado para | Tuberculose (TB) |
Também chamado de | Rifinah® (isoniazid with rifampicin); Rifater® (isoniazid with rifampicin and pyrazinamide); Voractiv®, Rimstar® (isoniazid with rifampicin, pyrazinamide and ethambutol) |
Disponível como | Comprimidos |
Isoniazid is used to treat tuberculose (TB). TB is a bacterial infection which mostly affects the lungs, but which can affect any part of your body. It is treatable with a course of medicines which usually lasts for six months in total. You will need to take several medicines to treat TB - isoniazid is just one of the medicines prescribed.
Isoniazid is usually prescribed as a tablet which contains a combination of two, three or four medicines to treat TB. The brand names of these are Rifinah®, Rifater®, Rimstar® and Voractiv®. You may be prescribed one or more of these brands at different times in your treatment. Taking combination medicines like these helps to reduce the total number of tablets you need to take each day.
Although isoniazid is a very effective medicine, it can sometimes cause damage to peripheral nerves (such as numbness and tingling sensations in the hands and feet). If you are considered to be at risk of this, your doctor will prescribe you a vitamin supplement of pyridoxine to prevent it.
Before taking isoniazid
Some medicines are not suitable for people with certain conditions, and sometimes a medicine may only be used if extra care is taken. For these reasons, before you start taking isoniazid it is important that your doctor knows:
If you are pregnant, trying for a baby or breastfeeding. Although isoniazid is not known to be harmful in pregnancy, it is important that you tell your doctor, as you may need to be given a vitamin supplement.
Se você tiver algum problema com o funcionamento dos seus rins ou do seu fígado.
If you have epilepsy or diabetes.
If you have ever had a mental health problem called psychosis.
If you drink a lot of alcohol, or if you do not eat a sufficient amount.
If you are HIV-positive.
If you know you have slow acetylator status. This means that your body may process isoniazid more slowly, leading to an increased risk of side-effects.
If you have a rare inherited blood condition called porphyria.
Se você estiver tomando outros medicamentos. Isso inclui quaisquer medicamentos que você esteja tomando e que estejam disponíveis para compra sem receita médica, bem como medicamentos fitoterápicos e complementares.
Se você já teve uma reação alérgica a um medicamento.
How to take isoniazid
Before you start treatment, read the manufacturer's printed information leaflet from inside the pack. It will give you more information about the brand of tablets you have been given and will provide you with a full list of the side-effects which you may experience.
It is important that you take the medicines to treat TB exactly as your doctor tells you to. You will be asked to take isoniazid every day. Your doctor will explain to you how many tablets to take each day, and this information will be printed on the label of the pack of tablets to remind you. If when you collect your supply of tablets you are unclear about how to take them, ask your pharmacist to explain.
The ideal time to take your tablets each day is half an hour before breakfast. If you forget, then take the tablets two hours after breakfast or wait until half an hour before your next meal. This is because isoniazid is absorbed better when your stomach is empty.
Obtendo o máximo do seu tratamento
It is important that you keep your regular appointments with your doctor. This is so your doctor can check on your progress. Your doctor will want you to have blood tests from time to time during treatment to make sure that your liver stays healthy.
Continue to take the tablets regularly unless your doctor tells you to stop. This is because it is important for you to complete the treatment course so that the infection does not come back. If for any reason you stop taking the tablets (such as if you think you may be developing side-effects - see also below) then you must let your doctor know about it straightaway so that you can be given alternative treatment.
If you buy any medicines, check with a pharmacist first that they are suitable for you to take with isoniazid. Some antacid preparations can reduce the amount of the medicine that your body absorbs.
Some foods may interact with isoniazid. Try to avoid eating foods containing histamine or tyramine. Examples include tuna fish, fermented or pickled products, strong cheeses, cured meats and red wine.
You should try to avoid drinking alcohol whilst taking isoniazid, as the combination could harm your liver.
Isoniazid may stop the oral typhoid vaccine from working. If you are having any vaccinations, make sure the person treating you knows that you are taking this medicine.
Se você for se submeter a uma operação ou a qualquer tratamento dentário, informe à pessoa que está realizando o tratamento quais medicamentos você está tomando.
Can isoniazid cause problems?
Along with their useful effects, most medicines can cause unwanted side-effects although not everyone experiences them. The table below contains the most common ones associated with isoniazid. You will find a full list in the manufacturer's information leaflet supplied with your medicine. Unwanted effects often improve as your body adjusts to a new medicine, but speak with your doctor or pharmacist if any become troublesome.
Common isoniazid side-effects | O que posso fazer se passar por isso? |
Tingling feelings, muscle weakness | Let your doctor know as soon as possible |
Tontura | If affected do not drive and do not use tools or machines until you feel better |
Sentindo-se mal (náusea) ou vomitando (vômito) | Stick to simple meals - avoid rich or spicy food. Drink plenty of liquid to replace any lost fluids |
Boca seca | Tente mascar chiclete sem açúcar ou chupar balas sem açúcar |
High temperature (fever), skin rash, hearing problems, mood changes, difficulty passing urine | Se algum desses se tornar problemático, fale com seu médico |
Importante: isoniazid on rare occasions causes liver problems. The symptoms include persistent sickness (nausea and vomiting), feeling very weak and yellowing of the skin and whites of the eyes (jaundice). If this happens to you, speak with your doctor or go to your local accident and emergency department straightaway.
If you experience any other symptoms which you think may be due to this medicine, speak with your doctor or pharmacist for advice.
How to store isoniazid
Mantenha todos os medicamentos fora do alcance e da vista das crianças.
Armazene em local fresco e seco, longe de calor e luz diretos.
Informações importantes sobre todos os medicamentos
Informações importantes sobre todos os medicamentos
Nunca tome mais do que a dose prescrita. Se suspeitar que você ou outra pessoa possa ter tomado uma overdose deste medicamento, vá ao departamento de acidentes e emergências do hospital local. Leve o recipiente com você, mesmo que esteja vazio.
Este medicamento é para você. Nunca o dê a outras pessoas, mesmo que a condição delas pareça ser a mesma que a sua.
Não guarde medicamentos vencidos ou indesejados. Leve-os à sua farmácia local, que se encarregará de descartá-los para você.
Se você tiver alguma dúvida sobre este medicamento, pergunte ao seu farmacêutico.
Relatar efeitos colaterais de um medicamento ou vacina
Se você sentir efeitos colaterais, pode relatá-los online através do Site do Yellow Card.

Inseguro sobre misturar medicamentos?
Verifique possíveis interações entre medicamentos, suplementos e alimentos antes de tomá-los juntos.
Perguntas frequentes
What is the typical duration of treatment with isoniazid for TB?
Treatment for tuberculosis (TB) usually lasts for six months in total. Isoniazid is one of several medicines you will need to take during this period.
How will I know what combination tablets I am prescribed and how many to take?
Isoniazid is often prescribed as a combination tablet with other TB medicines, and the brand name will vary. Your doctor will explain how many tablets to take daily, and this information will also be printed on the label of the tablet pack. If you are unsure when collecting your supply, ask your pharmacist for clarification.
Why do I need blood tests while taking isoniazid?
Your doctor will want you to have blood tests from time to time during your treatment to ensure that your liver remains healthy. This is an important part of monitoring your progress and managing any potential side effects of the medicine.
Are there particular foods I should avoid while on isoniazid?
Yes, some foods can interact with isoniazid. You should try to avoid foods containing histamine or tyramine, such as tuna fish, fermented or pickled products, strong cheeses, cured meats, and red wine.
What should I do if I am experiencing side effects from isoniazid?
If you experience any troublesome side effects, you should speak with your doctor or pharmacist for advice. If you develop persistent sickness (nausea and vomiting), feel very weak, or notice yellowing of your skin and eyes (jaundice), seek immediate medical attention by contacting your doctor or going to your local accident and emergency department, as these could be signs of rare but serious liver problems.
Leitura adicional e referências
- Manufacturer's PIL, Rifater® Tablets; Sanofi, O Compêndio Eletrônico de Medicamentos. Datado de agosto de 2021.
- Manufacturer's PIL, Rifinah® 150/100 mg Tablets; Sanofi, O Compêndio Eletrônico de Medicamentos. Datado de agosto de 2021.
- Manufacturer's PIL, Isoniazid 50 mg and 100 mg Tablets; RPH Pharmaceuticals AB, The electronic Medicines Compendium. Dated May 2022.
Sobre o autorVer biografia completa

Michael Stewart, MRPharmS
Gerente de Revisão de Folhetos de Medicamentos – Contratado, Farmacêutico
BPharm (Hons), MRPharmS
Michael é um farmacêutico comunitário atuando nas Midlands e em South Yorkshire, com mais de 20 anos de experiência em aconselhamento sobre medicamentos e condições médicas. Ele tem uma sólida formação em treinamento em saúde, tendo produzido e ministrado cursos de treinamento para equipes de farmácia e funcionários de ambientes de cuidados residenciais, incluindo enfermeiros. Ele também contribuiu para conselhos consultivos de farmácia para o manejo de condições de baixa gravidade na comunidade.
Sobre o revisor

Sid Dajani
Sultan Dajani se formou na Escola de Farmácia de Londres em 1994 e se tornou o membro mais jovem eleito para o conselho da Sociedade Real de Farmácia desde sua fundação em 1842.
Histórico do artigo
As informações nesta página são escritas e revisadas por clínicos qualificados.
Artigo também disponível em Inglês, Alemão, Espanhol, Francês, Italiano, Português, Hindi, Hebraico, Árabe, e Sueco.
Próxima revisão prevista: 3 de jan de 2028
4 Jul 2023 | Última versão

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