Like all medicines, amitriptyline can cause side effects in some people, but many people have no side effects or only minor ones.
Common side effects
Doses of amitriptyline for pain are lower than the doses for depression. This means the common side effects tend to be milder and go away within a few days.
Some of the common side effects of amitriptyline gradually improve as your body gets used to the medicine.
These common side effects of amitriptyline happen in more than 1 in 100 people. There are things you can do to help cope with them:
Constipation
Get more fibre into your diet such as fresh fruit, vegetables and cereals, and drink plenty of water. Try to exercise more regularly, for example, by going for a daily walk or run. If this does not help, talk to your pharmacist or doctor.
Feeling dizzy
This is probably due to low blood pressure. Amitriptyline can reduce your blood pressure when you stand up.
Drink plenty of water or other non-alcoholic drinks. Do not stand up too quickly after you've been sitting or lying down. Do not drive, cycle or use tools or machines if you feel dizzy.
Dry mouth
Chew sugar-free gum or suck sugar-free sweets.
Feeling sleepy or tired
Take amitriptyline in the evening. Do not drink too much alcohol. Do not drive, cycle or use tools or machinery if you feel sleepy or tired.
Difficulty peeing
Relax when you try to pee. Do not try to force the flow of pee. If you cannot pee, try again a short time later.
Talk to your doctor urgently if you cannot pee at all.
Headache
Make sure you rest and drink plenty of fluids. Do not drink too much alcohol. Try taking paracetamol or ibuprofen if you need pain relief.
Talk to your doctor if the headaches do not go away or are severe.
Speak to a doctor or pharmacist if the advice on how to cope does not help and a side effect is still bothering you or does not go away.
Serious side effects
It happens rarely, but some people have a serious side effect after taking amitriptyline.
Call a doctor or call 111 now if:
- you get a fast or irregular heartbeat
- the whites of your eyes turn yellow, or your skin turns yellow, although this may be less obvious on brown or black skin – these can be signs of a liver problem
- you have a headache, you feel confused or weak, or you get muscle cramps – these can be signs of a low sodium level in your blood
- you have eye pain, a change in your eyesight, or swelling or redness in or around your eye
Immediate action required: Call 999 if:
- you have weakness on one side of your body, trouble speaking or thinking, loss of balance or blurred eyesight – these can be signs of a stroke
- you have a seizure or fit
- you get severe chest pain – this can be a sign of a heart attack
Immediate action required: Call 999 or go to A&E if:
- you have thoughts about harming yourself or ending your life
Serious allergic reaction
In rare cases, it's possible to have a serious allergic reaction (anaphylaxis) to amitriptyline.
Immediate action required: Call 999 now if:
- your lips, mouth, throat or tongue suddenly become swollen
- you're breathing very fast or struggling to breathe (you may become very wheezy or feel like you're choking or gasping for air)
- your throat feels tight or you're struggling to swallow
- your skin, tongue or lips turn blue, grey or pale (if you have black or brown skin, this may be easier to see on the palms of your hands or soles of your feet)
- you suddenly become very confused, drowsy or dizzy
- someone faints and cannot be woken up
- a child is limp, floppy or not responding like they normally do (their head may fall to the side, backwards or forwards, or they may find it difficult to lift their head or focus on your face)
You or the person who's unwell may also have a rash that's swollen, raised, itchy, blistered or peeling.
These can be signs of a serious allergic reaction and may need immediate treatment in hospital.
Other side effects
These are not all the side effects of amitriptyline. For a full list see the leaflet inside your medicine packet.
You can report any suspected side effect using the Yellow Card safety scheme.