1. About dosulepin

Dosulepin is an antidepressant medicine. It's used to treat depression.

It's also occasionally used for some types of nerve pain, such as fibromyalgia, and to prevent migraines.

Dosulepin is available on prescription – usually only if you're already taking it and haven't had any serious side effects.

It comes as capsules and tablets.

2. Key facts

  • Dosulepin was commonly used as an antidepressant in the past. But these days doctors don't write new prescriptions for it unless it has been recommended by a specialist because of concerns about side effects.
  • If you're already taking dosulepin, your doctor will want to consider whether it's still the best treatment option for you. They'll only continue to prescribe dosulepin if a consultant or another specialist agrees with this decision.
  • Common side effects include constipation, feeling dizzy, a dry mouth, feeling sleepy, difficulty peeing, or headaches.
  • Dosulepin can cause extra side effects if you stop taking it suddenly. Talk to your doctor if you're thinking of stopping taking dosulepin.
  • Dosulepin is also known as dothiepin or by the brand name Prothiaden.

3. Who can and can't take dosulepin

Dosulepin is normally only prescribed if you're already taking it and haven't had any serious side effects.

If you haven't had dosulepin before, your doctor won't start you on it because of the risk of serious side effects. But occasionally it may still be the best choice of treatment for you.

If other treatments haven't helped you, your doctor may refer you to a specialist (such as a psychiatrist or pain consultant).

If the specialist thinks it is the best medicine for you, they may start you on dosulepin.

Most adults (aged over 18 years) can take dosulepin. But dosulepin isn't suitable, or the best option, for some people.

Check with your doctor if you:

  • have had an allergic reaction to dosulepin or any other medicine in the past
  • have a heart problem – dosulepin can make some heart problems worse
  • have a rare illness called porphyria
  • have liver or kidney problems
  • have epilepsy or are having electroconvulsive treatment – dosulepin may increase your risk of having a seizure
  • have an eye problem called glaucoma – dosulepin can increase the pressure in your eye
  • have thoughts about harming yourself or ending your life
  • are trying to become pregnant, are already pregnant or are breastfeeding

If you have diabetes, dosulepin may change your blood sugar level. For the first few weeks, check your blood sugar more often and talk to your doctor if it's too high or low.

4. How and when to take it

It's usual to take dosulepin once a day before bedtime. This is because it can make you feel sleepy.

If you're still feeling drowsy the next day, try taking it earlier in the evening.

Sometimes, if you're just starting treatment, your doctor may tell you to take a lower dose 2 or 3 times a day until you get used to the medicine. This will reduce the chance of side effects while you get used to the medicine.

Dosulepin doesn't usually upset your stomach, so you can take it with or without food.

Swallow the tablet or capsule whole with a drink of water. Do not chew it, as it tastes bitter.


Dosulepin comes in 2 different strengths – either 25mg capsules or 75mg tablets.

For depression, the usual dose of dosulepin is 75mg to 150mg a day. Your dose may slowly go up to 225mg a day if your specialist recommends it. The maximum dose for depression is 225mg a day.

For pain relief or preventing migraines, the usual dose is 75mg a day taken in the evening, but this may vary. Your dose may start at 25mg a day and be increased slowly to 75mg a day. The maximum dose of dosulepin for pain or migraine is 150mg a day.

What if I forget to take it?

If you take dosulepin once a day and forget a dose, don't worry. Take your next dose the next day at the usual time.

If you take dosulepin 2 or 3 times a day and forget a dose, take it as soon as you remember unless it's nearly time for your next dose.

Never take 2 doses at the same time to make up for a forgotten one.

If you often forget doses, it may help to set an alarm to remind you. You could also ask your pharmacist for advice on other ways to help you remember to take your medicine.

What if I take too much?

5. Side effects

Like all medicines, dosulepin can cause side effects, but many people have no side effects or only minor ones.

Common side effects

Some of the common side effects gradually improve as your body gets used to dosulepin.

Keep taking the medicine, but talk to your doctor or pharmacist if these side effects bother you or don't go away:

  • constipation
  • dizziness
  • a dry mouth
  • feeling sleepy, tired or weak
  • difficulty peeing
  • headaches

Serious side effects

It happens rarely, but some people have serious side effects after taking dosulepin. In particular, there's an increased risk of heart problems.

Call a doctor now if you get:

  • a fast or irregular heartbeat
  • yellow skin, or the whites of your eyes go yellow – these can be signs of a liver problem
  • constant headaches, long-lasting confusion or weakness, or frequent muscle cramps – these can all be signs of low sodium levels in your blood. In severe cases low sodium levels can lead to seizures
  • thoughts about harming yourself or ending your life
  • eye pain, a change in your eyesight, or swelling or redness in or around the eye
  • severe constipation or you're unable to pee and it's causing severe stomach pain

Call 999 now if you get:

  • weakness on one side of your body
  • trouble speaking or thinking
  • loss of balance, or blurred eyesight

These can be signs of a stroke. If you suspect that you or someone else is having a stroke, phone 999 immediately and ask for an ambulance

Serious allergic reaction

In rare cases, it's possible to have a serious allergic reaction (anaphylaxis) to dosulepin.

These are not all the side effects of dosulepin. For a full list, see the leaflet inside your medicine packet.

6. How to cope with side effects

What to do about:

  • constipation – eat more high-fibre foods, such as fresh fruit and vegetables and cereals. Try to have several glasses of water or other non-alcoholic drinks every day. If you can, it may also help to do some exercise. Watch a short video on how to treat constipation.
  • dizziness – this is probably due to low blood pressure (hypotension). Drink plenty of water or a non-alcoholic drink. Do not stand up too quickly after sitting or lying down.
  • dry mouth – chew sugar-free gum or sugar-free sweets.
  • feeling sleepy or tired – take dosulepin in the evening and cut down the amount of alcohol you drink. Do not drive or use tools or machinery if you're feeling sleepy. If this doesn't help, talk to your doctor.
  • difficulty peeing – relax when you try to pee. Do not try to force the flow of urine. If you can't go, try again later. Talk to your doctor urgently if you can't pee at all.
  • headaches – make sure you rest and drink plenty of fluids. Do not drink too much alcohol. Talk to your doctor if the headaches last longer than a week or are severe.

7. Pregnancy and breastfeeding

It's important for you and your baby that you stay well during your pregnancy. If you become pregnant while taking dosulepin speak to your doctor. Do not stop taking your medicine unless your doctor tells you to.

Dosulepin has been linked to a very small increased risk of problems for your unborn baby. However if your depression is not treated during pregnancy this can also increase the chance of problems.

You may need to take dosulepin during pregnancy if you need it to remain well. Your doctor can explain the risks and the benefits, and will help you decide which treatment is best for you and your baby.

Dosulepin and breastfeeding

If your doctor or health visitor says your baby is healthy, dosulepin can be used during breastfeeding.

Dosulepin passes into breast milk in very small amounts, and has not been linked with any side effects.

It is important to continue taking dosulepin to keep you well.

Breastfeeding will also benefit both you and your baby.

If you notice that your baby isn't feeding as well as usual, or seems unusually sleepy or restless, or if you have any other concerns about your baby, then talk to your health visitor or doctor as soon as possible

8. Cautions with other medicines

Many medicines and dosulepin can interfere with each other and increase the chances of side effects. In some cases, taking dosulepin with other medicines can cause serious side effects.

Make sure your doctor and pharmacist know what other medicines you are taking. This is important when you start or stop any other medicines, or when you have the dose changed.

Mixing dosulepin with herbal remedies and supplements

Do not take St John's wort, a herbal remedy for depression, while you're taking dosulepin. It'll increase your risk of side effects.

It's not possible to say whether other complementary medicines or herbal remedies are safe to take with dosulepin.

They're not tested in the same way as pharmacy and prescription medicines. They're generally not tested for the effect they have on other medicines.

9. Common questions

Page last reviewed: 13/12/2018
Next review due: 13/12/2021