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Agomelatine

Medication name

  • Agomelatine ("ag-o-mel-a-teen")

  • Brand name

    Valdoxan ("val-DOX-an")

  • Medication type

    Atypical antidepressant

Tablets: 25mg strength only

If you are 18 or over, your doctor can prescribe you agomelatine as a licensed medicine for depression.

If you are under 18, a specialist doctor may still consider this as a treatment option. This may be because other medicines haven’t worked for you, or because you’ve found the side effects of other medicines difficult to tolerate.

Read our guide to depression

About agomelatine

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 our brain chemicals, including noradrenaline, dopamine and serotonin.

Dopamine and noradrenaline are naturally occurring chemical messengers (or ‘neurotransmitters’) that have an important role in areas of the brain that control mood, thinking, feelings and emotions. Depression can reduce the levels of these brain transmitters.

Depression also affects a chemical called melatonin, which is linked to your sleep patterns.

Agomelatine can increase melatonin activity directly. It does this by acting like melatonin at the melatonin receptors (the target sites where melatonin works). By increasing melatonin activity, agomelatine also directly increases activity of noradrenaline and dopamine.

Depression, and other conditions like anxiety disorders, are not just caused by low levels of neurotransmitters, but a rise in these can improve symptoms and help you to feel better.

Agomelatine and everyday life

Agomelatine should start helping with depression within one to two weeks. It may take four weeks or longer for you to get the full effect.
Your doctor will probably start you on the standard dose of 25mg a day and then increase it to 50mg after two weeks if there has not been much improvement.

How people respond to treatment can vary. Sometimes improvement is slow, and you may not feel any different to start with. This can be hard when your mood is low, and if you experience any side effects from your medication you may think you feel worse and not better. If you can, give your medication a chance to work and continue to take it for at least three to four weeks to see if it makes a difference.

Your parents, friends and doctor may notice an improvement in you before you feel it yourself, so it’s a good idea to talk to them.

If you think your medicine has not made any difference to how you feel after three to four weeks, you should go back to your doctor. They might recommend a change in dose or a different medication. However, it can take longer to work for some people than for others, so they may suggest you wait six to eight weeks before deciding.

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 not possible to predict how agomelatine will affect each person before they start taking it. Talk to your doctor or pharmacist if you are concerned about your weight, or changes to your weight, while taking agomelatine.

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.

Agomelatine may make you feel drowsy for a few days after you start taking it. This should pass after the first week or two. It is recommended that you take this medicine at bedtime.

Insomnia is also a commonly reported side effect of this medicine.

Talk to your doctor or pharmacist if you are concerned about how agomelatine is affecting your sleep.

If you have been taking agomelatine for more than a month and you continue to feel very tired, sleepy or unable to function well during the day, you should go back to your doctor and discuss what changes could be made to help. This may include switching to a different medication.

Alcohol

It may be possible to drink alcohol in small amounts while taking agomelatine. But the two together might make you feel very sleepy and unsteady on your feet, especially when you first start taking the medication.

During the first few weeks of treatment, it is recommended that you don’t drink alcohol until you know how the medicine affects you.

Drinking alcohol every day, or in large amounts, can make your symptoms worse and may mean you won’t get the maximum benefit from your medication.

Street drugs

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.

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

There are many other street drugs, but we don’t know what effect taking them with agomelatine will have, so it’s best to be cautious.

There is no regulation of street drugs or ‘legal highs’, so even if there are no known issues with the medication you take, the supply you receive might be mixed with other substances that could be dangerous.

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.

Your doctor can give you advice and help with stopping smoking.

Get more advice on drugs and alcohol.

Agomelatine does not mix well with some other medicines, including herbal remedies. It may affect how they work or could cause more side effects. 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.

Before you start taking agomelatine, tell your doctor if you are taking any other medications, including things you have bought from a pharmacy or other shop for common illnesses like colds and flu or medications that you put on your skin.

Always tell the pharmacist that you are taking agomelatine if you buy any medicines from a pharmacy.

Look at the leaflet inside your medicine box for more information about other medicines that can interact with agomelatine. With some medicines your doctor may need to adjust the dose of your medicines if you take them together. Ask a doctor or pharmacist for more information if you have any questions.

The tablets may not be suitable for you if you have problems eating some sugars or dairy foods, as the Valdoxan brand of agomelatine contains lactose.

Always let your pharmacist know if you have any food allergies or intolerances, and always check with them if you’re concerned about any of the ingredients in your medication.

If you need to avoid animal products such as gelatine, please note that this is often found in capsules but also in some tablet formulations. Ask your pharmacist if you have any questions about the ingredients. Find out more on the Vegan Society website.

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 or weeks until you know how it affects you.

Most people drive as normal while taking agomelatine. If you are worried about this or have any concerns you would like to discuss, speak to your doctor or pharmacist.

Pregnancy

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

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 discuss the benefits and risks of continuing agomelatine and help you to make a decision that is best for you and your baby. They may refer you to a specialist perinatal mental health team to support you with this decision. You can find out more information about taking agomelatine during pregnancy at Bumps (Best Use of Medicines in Pregnancy).

Untreated depression or anxiety can also be harmful to you and your developing baby, so decisions about stopping or avoiding medication when you are pregnant need to be discussed carefully with your doctor. If you and your doctor agree that it is best for you to continue taking agomelatine while pregnant, you should tell your midwife. If you are planning to get pregnant, it is recommended that you take folic acid while you are trying for a baby and during pregnancy. It is safe to take this together with agomelatine.

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. Talk to your midwife and doctor about feeding options.

If you breastfeed while taking agomelatine and your baby becomes restless, very sleepy or develops feeding problems, seek medical advice urgently.

Sex

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

Untreated depression or anxiety can have a negative effect on your sex life, so if agomelatine helps you to recover, positive effects can include improving your desire, experience and enjoyment of sex as your mood lifts and you become interested in life and relationships again.

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 containing 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.

Talk to your doctor about agomelatine if you are trying to get pregnant or planning a family.

Agomelatine is not a banned substance in sport.

Most people play sports as normal while taking agomelatine. However, it may affect your ability to play sports that require a lot of focus. It might be best to stop these sports for the first few days until you know how it affects you or the effects get better.

If you have any concerns, discuss this with your doctor.

Ideally it’s best not to take agomelatine for the first time just before your exams, as it may affect your concentration.

It’s not possible to predict how the medication will make you feel, and if you do get any side effects, these are more likely to occur when you first start taking agomelatine.

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 and ability to study. Bear in mind that depression itself can also affect concentration.

Most people take exams as normal while taking agomelatine, but if you have any concerns, discuss this with your doctor.

Information and safety considerations

  • Your doctor will consider any other medical conditions or symptoms you have before recommending a medicine for you.

    Your medicine will come with a ‘patient information leaflet’. It’s important that you read this information. Speak to your pharmacist if:

    • you’re not given a leaflet
    • you don’t understand the information
    • you need it in a different format or language
    • you’re concerned about something you’ve read

    The information leaflet also includes a list of warnings and precautions to consider before you take the medicine. If you think that any of these apply to you and are concerned that your doctor is not already aware of them, check with your doctor or pharmacist before you start to take your medication (or as soon as possible if you are already taking it).

    You can view the patient information leaflet on the Electronic Medicines Compendium (EMC). Visit the EMC website and search agomelatine. 

About this information

The information on this page was reviewed by the College of Mental Health Pharmacy in September 2024.

Visit the CMHP website
College of mental health pharmacy logo.

CMHP. College of Mental Health Pharmacy

About this information

The information on this page was reviewed by the College of Mental Health Pharmacy in September 2024.

Visit the CMHP website
College of mental health pharmacy logo.

CMHP. College of Mental Health Pharmacy

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