Amitriptyline for nerve pain and migraine prevention

The NHS describes amitriptyline as a medicine used to treat nerve pain and pain that lasts a long time, and to help prevent migraines. It is only available on prescription as tablets or liquid. Though it is an antidepressant, the doses used for pain are lower and the effects are not the same as when taking it for depression.

It is thought to work by raising serotonin in the brain, which can change how nerves receive pain signals. Many people also find it helps them sleep.

Adults and young people aged 12 to 17 usually start on 10mg a day and the doctor can increase it if needed. Children aged 11 and under are started on a dose based on weight and symptoms. It is normally taken once a day before bed, and if you feel drowsy in the morning you can try taking it earlier in the evening. It can be taken with or without food, and tablets should be swallowed whole because they taste bitter if chewed.

The NHS says to allow at least 6 weeks before judging whether it works. Do not give up after a week or two. People may take it for many months or even years, but it should be reviewed regularly with a doctor.

Because doses for pain are lower, common side effects tend to be milder and go away within a few days. They include constipation, dizziness (probably from lower blood pressure on standing), dry mouth, feeling sleepy or tired, difficulty peeing and headache. Sexual side effects are not common and should settle after the first couple of weeks; if they do not, go back to your doctor.

Call a doctor or 111 for a fast or irregular heartbeat, yellowing of the skin or eyes, headache with confusion, weakness or muscle cramps (possible low sodium), or eye pain, vision changes or eye swelling. Call 999 for signs of a stroke, a seizure, or severe chest pain, and 999 or A&E if you have thoughts of harming yourself or ending your life. Vaginal bleeding after the menopause should be checked promptly.

Most adults can take it, and children aged 2 and over can take it for some types of nerve pain. Tell your doctor if you have had an allergic reaction to it, have a heart problem, liver or kidney problems, epilepsy, have ever taken medicines for depression, are pregnant, trying to conceive or breastfeeding, have glaucoma, have thoughts of self-harm, or have type 1 or type 2 diabetes. It may affect blood sugar, so people who test regularly may need to do so more often for the first few weeks.

Pregnancy: it can be taken and is not thought to be harmful to the baby, though paracetamol is usually the first choice and amitriptyline may be recommended if other painkillers do not work. Breastfeeding is possible if the baby is healthy; amitriptyline passes into milk in very small amounts. Avoid bed-sharing. There is no evidence it affects fertility.

Opioid painkillers such as codeine, morphine or oxycodone taken with amitriptyline can increase the risk of becoming very drowsy and having breathing problems. Some antidepressants can affect how it works and cause very high blood pressure, even after you stop them, so tell the doctor about any past antidepressant. Do not take St John's wort with it. Cannabis can make you very sleepy and speed up your heart.

You can drink alcohol, but it may make you sleepy, so it is usually best to avoid it until you see how amitriptyline affects you. In the first few days avoid driving, cycling and machinery until you know how it makes you feel.

Less is known about long-term effects than short-term ones. The NHS notes there may be an increased risk of confusion and possibly dementia with medicines like amitriptyline, but more research is needed, and your doctor will review treatment regularly. Other options for nerve pain, long-term pain or migraine prevention include duloxetine, paracetamol, pregabalin, propranolol, physiotherapy, CBT, exercise and acupuncture.

Stopping suddenly can cause flu-like symptoms such as nausea, muscle pain, tiredness and restlessness, so doctors usually reduce the dose over several weeks, or longer after prolonged use. Do not stop without talking to your doctor. If you take too much, it can cause a change in heartbeat or seizures and needs urgent help.