Agomelatine

How it works

What does agomelatine do?

Agomelatine is an antidepressant used to treat depression.

The brain is usually good at making sure we have enough of the chemicals we need to function properly. But depression can affect a number of brain chemicals.

One such chemical is serotonin; depression reduces serotonin levels.

Another chemical depression affects is melatonin. Reduced melatonin is linked to disturbances in our sleep patterns.

Agomelatine is the first antidepressant to increase melatonin activity directly. It does this by acting like melatonin at the target sites where melatonin (these are known as the melatonin receptors).

Agomelatine also affects serotonin in two helpful ways.

By increasing melatonin activity, agomelatine also increases serotonin activity. If serotonin activity is increased at all target sites, this can cause a number of side effects, most of which are linked to one particular target site (5HT_2c). However, the second helpful way agomelatine affects serotonin is by blocking serotonin from getting to this particular (5HT_2c) target site.

How long does agomelatine take to start working?

It can take up to four weeks for agomelatine to have its full effect, but it should start to help within the first one to two weeks if you are taking it for depression.

Your doctor will probably start you on the standard dose of 25mg a day and then increase it to 50mg a day after two weeks if there has not been much improvement.

How long will I need to take agomelatine?

You and your doctor should talk about how long you need to take agomelatine.

Most people take it for about six months. If you doctor prescribed you agomelatine for depression, you should probably take it for at least six to nine months, otherwise your symptoms can come back.

People who have had low mood or depression more than once may take agomelatine for a couple of years or more. This is to prevent the depression or low mood from returning.

Never stop taking agomelatine suddenly, as this may cause the low mood or depression to return. Ask your doctor or pharmacist for advice on how to stop taking it safely.

It can take a month before this medication has its full effect and you see positive results. By the end of the first month, you should feel your mood lift, have more interest in things and start to enjoy things you used to enjoy again. Let your doctor know if you do not feel better after a month.

If you do not feel any different after a month and are already on 50mg a day, you may need something different. Carry on taking the medicine and go back to your doctor as soon as possible.

Your doctor needs to know if...

You need to talk to your doctor or pharmacist before taking agomelatine if you have, or have ever had:

• liver disease

Your doctor should test your liver function with a blood test before you start taking agomelatine. You should then have follow-up blood tests after three, six, 12 and 24 weeks of treatment. This is because up to one in 400 patients on the higher dose of agomelatine may need to stop treatment due to liver enzyme changes.

Let your doctor know if you have problems eating some sugars or dairy (milk-based) products, as the Valdoxan brand of agomelatine contains lactose.

Taking agomelatine

How can agomelatine be taken?

Agomelatine only comes in the form of 25mg-strength tablets.

You should only take agomelatine as agreed with your doctor

You will get the best effect from agomelatine if you take it regularly every day at the dose prescribed by your doctor.

Make sure that you know your dose. If it's not written on the label, check with your pharmacist or doctor.

You should start by taking agomelatine in the evening. This will help with your sleep.

To make sure you take your medication at the same time every day, try to get into a routine, like taking it when you have supper or brush your teeth.

You can take it before or after food - it doesn't matter.

Swallow the tablet with a drink of water or liquid - if you chew it, it tastes bitter.

The Valdoxan brand of agomelatine may not be suitable for you if you have problems eating some sugars or dairy (milk-based) products, as it contains lactose.

What if I miss a dose?

If you forget to take a dose, then just take it as soon as possible. However, if you realise you forgot to take your last dose by the time you are due to take your next dose, only take your next dose.

Do not take a double dose.

What will happen if I forget to take my agomelatine?

If you forget to take your agomelatine for a few days, you may start to lose any positive effects you have seen while taking it.

If you want to stop taking agomelatine, please speak to your doctor first, as it is better to stop taking it under medical supervision.

Stopping the use of agomelatine

Stopping the medication causes the balance of chemicals in the brain to change.

When you start taking agomelatine, the brain adjusts to having a higher level of melatonin and serotonin around. If you stop taking the medication suddenly, the levels of these chemicals in the brain will change, and your brain can take a while to adapt to this change.

Stopping this medication quickly is unlikely to cause uncomfortable symptoms, but you may lose any positive effects you have seen while taking it.

You will not get addicted to this medication.

You can stop taking agomelatine safely with the help of your doctor.

The information on this page was reviewed by the College of Mental Health Pharmacy in October 2019.

Safety headlines

If you have taken more agomelatine than the dosage recommended by the doctor who prescribed it to you, you must get medical help immediately – even if you do not feel any different.

As part of depression, some people think about hurting themselves or develop suicidal feelings. Antidepressant medication will not stop this. You must get urgent help if you are having these sorts of thoughts. Speak to someone about it or go straight to hospital with your tablets.

Some people may find that thoughts of hurting themselves or taking their own lives get worse in the first few weeks after starting to take agomelatine. You must go straight to hospital with your tablets if you have any of these thoughts.

Agomelatine can sometimes cause other serious side effects, including allergic reactions (symptoms include: difficulty breathing, swelling of your face or throat, and itching skin lumps) and damage to your liver (dark urine, light-coloured poo, yellowing of the skin and eyes, pain in the upper-right belly, and sudden and unexplained tiredness). Go to a hospital with your medication straight away if you get any of these symptoms.

Stopping agomelatine suddenly is unlikely to cause unpleasant withdrawal symptoms, but you may become unwell again. Go to your doctor if you want to stop or are thinking of stopping.

Agomelatine is a fairly new medicine, so there is still very little information about the safety of taking it while pregnant, but no direct evidence that it is harmful. If agomelatine is helping to keep you well, then stopping it may lead to you becoming unwell again. Becoming unwell may cause more harm to your developing baby than staying on the medicine. Talk to your doctor or midwife about this and get their help.

When to go to the hospital

If you have taken more agomelatine than the dosage recommended by the doctor who prescribed it to you, you must get medical help immediately – even if you do not feel any different. Go to A&E. Take your medicine with you to show to the doctors. Tell them how much you have taken. Get a friend or family member to go with you if you can, in case you feel ill on the way.

You might get any of the following signs:

• excessive sleepiness
• stomach pains

You should also stop taking agomelatine and go to a doctor or hospital straight away if you get any of the following symptoms:

• difficulty breathing
• swelling of your face, lips, tongue or throat to the extent that you cannot swallow or breathe
• really bad itching of the skin (with raised lumps)
• signs of potential liver injury (dark urine, light-coloured poo, yellowing of the skin and eyes, pain in the upper-right belly, and sudden and unexpected tiredness)

Go to your doctor or the hospital straight away, but don't stop taking agomelatine if you get any of the following symptoms:

• you start having seizures (fits) for the first time (or, if you have had seizures in the past, the frequency of seizures increases)
• your behaviour changes because you feel very happy or over-excited

Side effects

Some of the side effect you may get when you start taking agomelatine should get better or disappear after a few days. If they do not, or they get worse, you should go back to your doctor.

If you get any side effects not listed here please look at the patient leaflet in the medicine pack, or speak to your pharmacist or doctor.

Very common side effects, which affect more than one in ten people, include:

• headache

Other common side effects, which affect up to one in ten people, include:

• anxiety
• nausea and vomiting
• stomach pain
• abnormal dreams
• insomnia
• dizziness
• drowsiness and fatigue
• increase in weight
• change in bowel habits
• back pain
• changes in liver enzymes (this is why it is important to ensure you have regular blood tests)

There are other side effects you can get when taking this medicine. We have only included the most common ones here.

Please do not worry about these side effects. Some people will not get any side effects at all.

If you think you are getting side effects from taking agomelatine, speak to your doctor or pharmacist.

If you do get a side effect, please think about reporting it via the 'Yellow Card' system.

Body

Some people find that, in the long term, they gain a little weight while taking agomelatine. This may be due in part to their appetite returning.

Some people may find that their weight goes down while taking agomelatine, although this is rarer.

It is very difficult to know how agomelatine will affect each person who takes it. If you start to notice a change in your weight while taking agomelatine, talk to your doctor or pharmacist.

Sleep

Agomelatine may make you feel drowsy for a few days after you start taking it. This should pass after the first week or two.

If you feel like a zombie, and you've been taking it for more than a month, you should speak to your doctor.

Sex and fertility

Sex

Agomelatine is unlikely to cause side effects that will directly affect your sex life.

Fertility

There is no evidence to suggest that taking agomelatine will affect your fertility.

Agomelatine will not affect how contraceptive pills or the 'morning after' pill work. Contraceptive pills conntaining oestrogen are likely to increase the level of agomelatine in your body, but studies have shown that there is no need to reduce your dose of agomelatine.

Taking agomelatine should not affect your periods.

Pregnancy and breastfeeding

Pregnancy

There is no evidence to suggest that taking agomelatine while you are pregnant is harmful, but there is not much information available.

Talk to your doctor if you are trying to get pregnant while taking agomelatine.

If you do become pregnant while you are on agomelatine, you should carry on taking your medicine and speak to your doctor about this as soon as possible. They can help you decide whether or not to continue taking agomelatine.

If you do stop taking agomelatine and become unwell, this may be more harmful to your baby than staying on the medicine.

If you and your doctor agree that it is best for you to continue taking agomelatine while pregnant, you should tell your midwife.

Breastfeeding

There is no specific information about whether agomelatine is passed on to the baby through breastmilk, but since this is the case with most other drugs, it is likely that it is also the case with agomelatine.

If your baby was born early, then breastfeeding is not recommended as your baby may not safely be able to get rid of the agomelatine.

If your baby becomes restless, very sleepy or develops feeding problems, stop breastfeeding and seek medical advice urgently.

Please talk to your midwife, doctor or pharmacist if you want to breastfeed while taking agomelatine.

Driving and transport

Do not drive a car or ride a bike just after you start taking agomelatine.

Taking agomelatine may affect your ability to do things like drive a car, ride a bike, or anything else that needs a lot of focus. It might be best to stop doing these things for the first few days, until you know how it affects you.

Do not worry - most people do these things as normal while taking agomelatine.

School and exams

Try not to take agomelatine for the first time just before your exams, as it may affect your concentration.

You should talk to your doctor about any future exams if you are starting agomelatine.

You might decide together to delay starting it until you have done them.

If they are more than a month away, however, you might find that it is better to start agomelatine to improve your motivation to study.

Bear in mind that depression itself can also affect concentration.

Do not worry though - most people take exams as normal while on agomelatine.

Friends and family

You may want to let your family and friends know you are taking agomelatine so they can support you and help you look out for side effects.

For guidance on this, check out our page on getting support with your medication.

Sport

Agomelatine is not a banned substance in sport.

It may affect your ability to play sports that require a lot of focus, so it is a good idea to stop doing these sports for a short while until you know how it affects you.

Do not worry - most people play sports as normal while taking agomelatine.

Alcohol, street drugs and smoking

Alcohol

You can continue to drink alcohol in small amounts while taking agomelatine. You are likely to find that alcohol makes you feel more sleepy, so it might be best to stop drinking alcohol for a short while until you see how agomelatine affects you.

Street drugs

We do not know exactly how agomelatine interacts with street drugs and legal highs.

However, using cannabis while on agomelatine can make drowsiness worse and slow your reaction time.

Cannabis and other drugs may have their own side effects on your mental health, like anxiety or psychosis. For more information, have a look at our drugs and alcohol page.

Using heroin or methadone while on agomelatine can make drowsiness worse.

Smoking

Smoking affects the level of agomelatine in your body. If you smoke, then your body breaks agomelatine down more quickly. This means you may need a higher dose for the medicine to be effective.

If you stop smoking while taking this medicine, then your agomelatine levels will go up, meaning you may need to lower your dose so you don't get side effects.

Moving to nicotine replacement therapies or vaping will have the same effect on agomelatine levels as stopping smoking. This is because it is the chemicals in the smoke that cause your liver to break down the agomelatine more quickly.

If you smoke, or are thinking about stopping, then please speak to your doctor about this. They can give you advice and help with stopping smoking.

Prescription medicines

Agomelatine can interact with some other medicine and drugs. Always talk to your doctor if you are taking other medicines.

Do not take agomelatine if you are taking the herbal remedy St. John's Wort. St. John's Wort is a herbal medicine available over the counter in shops that can also be used for low mood. It does not mix well with any antidepressant, so please tell your doctor or pharmacist if you are trying this or want to try it.

Tell the pharmacist you are taking agomelatine when you buy medicines from a pharmacy, including things you put on your skin.

References and further reading

For more helpful links and information, have a look at our references and further reading page.