Cycloserine is one of several medicines you will need to take to treat tuberculosis (TB).
You will need to have regular blood tests while you are taking the capsules.
It is important that you take your doses regularly, every 12 hours.
|Type of medicine||An antituberculosis medicine|
|Used for||Tuberculosis (TB)|
Cycloserine is used to treat tuberculosis (TB). TB is a bacterial infection which mostly affects the lungs, but which can affect any part of your body. TB is treatable with a course of medicines which usually lasts for six months. You will need to take several medicines to treat TB - cycloserine is one of the medicines used. Cycloserine will be prescribed for you if other more frequently prescribed antituberculosis medicines are either not suitable for you, or have not been effective for you.
Cycloserine works by acting on the cell walls of the germs (bacteria) responsible for the TB. The cell walls do not form correctly which causes them to break, killing the bacteria.
Cycloserine will be prescribed for you by a doctor who specialises in the treatment of TB. It is important that you take it regularly.
Before taking cycloserine
Some medicines are not suitable for people with certain conditions, and sometimes a medicine can only be used if extra care is taken. For these reasons, before you start taking cycloserine it is important that your doctor knows:
- If you are pregnant or breastfeeding.
- If you drink a lot of alcohol.
- If you have any mental health problems, such as anxiety, depression or psychosis.
- If you have any problems with how your liver works, or any problems with the way your kidneys work.
- If you have a condition that causes fits, such as epilepsy.
- If you have a rare inherited blood disorder called porphyria.
- If you are taking any other medicines. This includes any medicines which are available to buy without a prescription, as well as herbal and complementary medicines.
- If you have ever had an allergic reaction to a medicine.
How to take cycloserine
- Before you start the treatment, read the manufacturer's printed information leaflet from inside the pack. It will give you more information about cycloserine and will provide you with a full list of the side-effects which you could experience from taking it.
- Take the capsules exactly as your doctor tells you to. As a guide, the usual dose to begin with in adults is one capsule twice a day, taken 12 hours apart (morning and evening). After two weeks, your dose may be increased to two capsules twice a day, depending on the result of a blood test.
- Try to take your doses of cycloserine at the same times of day each day, as this will help you to remember to take your doses regularly. You can take the capsules either with or without food.
- If you forget to take a dose, take it as soon as you remember. Try to take the correct number of doses each day, but do not take two doses at the same time to make up for a missed dose.
Getting the most from your treatment
- It is important that you keep your regular appointments with your doctor, or clinic. This is so your doctor can check on your progress. Your doctor will want you to have blood tests during the treatment, to make sure you have just the right amount of the medicine in your bloodstream. For some people, these tests can be as regular as once a week.
- Continue to take the capsules regularly - do not stop taking cycloserine unless your doctor tells you to stop. This is because it is important for you to complete the course of medicine so that the infection does not come back. Your treatment will last for several months.
- Do not to drink alcohol while you are on cycloserine. Cycloserine causes drowsiness, and drinking alcohol will increase the chance that you experience this side-effect. It also increases the risk of more serious side-effects, such as fits (convulsions).
- Cycloserine can stop the oral typhoid vaccine from working properly. If you are due to have any vaccinations, make sure that the person treating you knows you are taking this medicine. Also, if you are due to have an operation or any dental treatment, you should tell the person carrying out the treatment that you are taking cycloserine for TB.
- If you buy any medicines 'over the counter', check with a pharmacist that they are suitable for you to take alongside your prescribed medicines.
Can cycloserine cause problems?
Along with their useful effects, most medicines can cause unwanted side-effects although not everyone experiences them. The table below contains some of the ones associated with cycloserine. You will find a full list in the manufacturer's information leaflet supplied with the medicine. The unwanted effects often improve as your body adjusts to the new medicine, but speak with your doctor or pharmacist if any of the following continue or become troublesome.
|Cycloserine side-effects||What can I do if I experience this?|
|Headache||Drink plenty of water and ask your pharmacist to recommend a suitable painkiller. Let your doctor know if the headache continues|
|Feeling dizzy or sleepy, a spinning sensation (called vertigo)||Do not drive and do not use tools or machines. Do not drink alcohol|
|Feeling shaky, fits, feeling confused, mood or character changes, allergic skin rashes||Let your doctor know as soon as possible if you experience any of these|
|Changes to the results of some blood tests (such as those checking your liver and blood)||Your doctor will monitor for these|
If you experience any other symptoms which you think may be due to the capsules, please speak with your doctor or pharmacist for further advice.
How to store cycloserine
- Keep all medicines out of the reach and sight of children.
- Store in a cool, dry place, away from direct heat and light.
Important information about all medicines
Never take more than the prescribed dose. If you suspect that you or someone else might have taken an overdose of this medicine, go to the accident and emergency department of your local hospital at once. Take the container with you, even if it is empty.
This medicine is for you. Never give it to other people even if their condition appears to be the same as yours.
Do not keep out-of-date or unwanted medicines. Take them to your local pharmacy which will dispose of them for you.
If you have any questions about this medicine ask your pharmacist.
Further reading and references
Manufacturer's PIL, Cycloserine 250 mg capsules; King Pharmaceuticals Ltd, Medicines and Healthcare products Regulatory Agency (MHRA). Dated January 2018.
British National Formulary, 77th Edition (Mar 2019); British Medical Association and Royal Pharmaceutical Society of Great Britain, London.