Baclofen: muscle spasm relief and why stopping must be slow

The NHS describes baclofen as a muscle relaxant used to ease muscle spasms, cramps or tightness caused by conditions that affect the nerves and brain. It names cerebral palsy, motor neurone disease and multiple sclerosis. It is prescription-only.

It works on the nervous system rather than the muscle, so it is not a general treatment for ordinary back strain or sports injuries.

Baclofen usually comes as tablets or a liquid, taken three times a day. The doctor may start low and increase after a few days depending on how well symptoms improve, which reduces the chance of side effects. Try to take it at the same time each day, with food or a glass of milk (particularly if it makes you feel sick), swallow tablets whole and measure liquid with the syringe or spoon supplied.

A hospital specialist may sometimes prescribe baclofen as an injection or through a pump. If you miss a dose, take it when you remember unless the next dose is close, then skip it. Never take two together. An extra dose can be dangerous, so get medical help if you take more than prescribed.

Common effects are headaches, dry mouth, tiredness or weakness, dizziness or feeling faint, nausea or vomiting, eyesight problems, mood changes, and muscle weakness or pain. If you feel dizzy, tired or have eyesight problems, do not drive, ride a bike or use machinery until it passes. If side effects bother you, speak to a pharmacist or doctor and keep taking the medicine unless advised to stop.

Serious effects are rare: anaphylaxis, liver problems (yellowing of the skin and whites of the eyes), difficulty breathing, and very low mood with suicidal thoughts. Call 999 for anaphylaxis or breathing difficulty, and call 111 if you have thoughts of harming yourself or think you have any other serious side effect.

Most adults and children aged 1 month and over can take it. Tell your doctor if you have had an allergic reaction or serious side effect from it before, have a liver or kidney condition, epilepsy, diabetes or Parkinson disease, have had a stroke, have a mental health condition, or have problems with alcohol or drug dependence.

It is worth knowing that lower muscle tone is not always helpful: some people rely on a degree of muscle tightness to stand or walk, so the dose is a balance that your clinician adjusts with you.

Tell your doctor if you are pregnant or trying to get pregnant. You may be able to take it in pregnancy if the benefits outweigh the risks, and your baby may need to be closely monitored after birth for possible withdrawal symptoms.

You may be able to take it while breastfeeding, but check with a pharmacist or doctor first, as they may want to recommend a different muscle relaxant. Speak to a professional or call 111 if you have concerns about your baby.

The NHS lists other muscle relaxants such as tizanidine, mental health medicines such as lithium or amitriptyline, blood pressure medicines such as diltiazem, Parkinson medicines such as co-beneldopa or co-careldopa, sedating antihistamines such as promethazine or sedatives such as temazepam, and opioid painkillers such as morphine or buprenorphine.

It is best not to drink alcohol while taking baclofen, as it increases the risk of feeling very tired or sleepy. If you need to stop, do not do it suddenly because it may cause withdrawal symptoms. Your doctor will reduce the dose gradually over several weeks or months.