Venlafaxine

Medication name

Venlafaxine ("ven-la-FAX-een")
Brand name

Efexor XL® ("e-FEX-or")

There are lots of different ‘branded generic’ products available. Names include: Venladex, ViePax, Sunveniz, Venladex, Majoven, Vencarm, Venablue, Politid, Venaxx, Venlasov, Vensip and Venzip.
Medication type

Serotonin and noradrenaline re-uptake inhibitor (SNRI)

Tablets: 37.5mg and 75mg strengths

Modified-release (long-acting) tablets: 37.5mg, 75mg, 150mg,225mg and 300mg strengths

Modified-release (long-acting) capsules: 37.5mg, 75mg,150mg and 225mg strengths

Oral solution: 37.5mg/5ml and 75mg/5ml (sugar-free)

If you are 18 or over, the doctor can prescribe venlafaxine for you as a licensed medicine for depression, social anxiety disorder, generalised anxiety disorder, and panic disorders.

If you are under 18, a specialist doctor may still consider this as a treatment option.

Read our guide to depression

About venlafaxine

Venlafaxine is a type of antidepressant known as a serotonin-noradrenaline reuptake inhibitor (SNRI).

Serotonin (also called '5HT') 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. Research suggests that depression is more likely to occur when the brain doesn’t have enough serotonin and noradrenaline.

SNRIs like venlafaxine are thought to work by increasing levels of serotonin and noradrenaline in the brain. They can also cause an increase in dopamine (another naturally occurring neurotransmitter).

As the dose of venlafaxine is increased, it becomes more effective at increasing noradrenaline. However, its effect on serotonin and dopamine stays much the same. This means that some people may not get the full benefit of venlafaxine until they are on a higher dose.

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

Venlafaxine and everyday life

Venlafaxine 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 start with a low dose, which they will increase slowly to a dose that is effective for you. This may take several days or weeks.

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 form 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.

For anxiety, it may take longer for the benefits to be noticed. It could take up to three months before you feel the full benefit.

For some people, anxiety symptoms briefly increase at the start of treatment, but this should decrease over time. To avoid or minimise this, your doctor will usually start treatment with a low dose and increase this after one to two weeks.

A very common side effect of venlafaxine is a dry mouth. Over a long time, this can increase your risk of developing tooth decay or gum disease. Make sure you brush your teeth well and have regular dental check-ups. Speak to your dentist, doctor or pharmacist about things you can do to help.

Venlafaxine can also cause weight gain or weight loss.

It is not possible to predict how venlafaxine 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 venlafaxine.

You may want to let your family and friends know you are taking venlafaxine 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.

You can feel drowsy in the first few days of taking venlafaxine. This should get better after the first week or two.

Venlafaxine can also disrupt your sleep. You might experience insomnia (difficulty getting to sleep) and vivid dreams or nightmares.

If you have been taking venlafaxine for more than a month and you continue to feel very tired, sleepy or struggle to function 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 some alcohol while taking venlafaxine but having the two together might make you 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

Cannabis can make drowsiness worse with venlafaxine.

Cannabis and other drugs may have their own side effects on your mental health, like anxiety or psychosis.

Methadone and heroin can make drowsiness worse with venlafaxine.
Taking venlafaxine with cocaine, ecstasy or amphetamines could bring on serotonin syndrome. You could get a high temperature/fever, agitation, confusion, trembling or weird muscle movements. You need to go to hospital if this happens. Tell the doctor everything that you have taken.

There are many other street drugs, but we don’t know what effect taking them with venlafaxine 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.

Get more advice on our drugs and alcohol guide.

Venlafaxine does not mix well with some other medicines, including herbal remedies. It may affect how they work or could cause more side effects. Always tell the pharmacist that you are taking venlafaxine if you buy any medicines from a pharmacy.

Do not take venlafaxine if you are taking or have taken MAOIs (like isocarboxazid, moclobemide, phenelzine or tranylcypromine) in the last 14 days. You must wait until 14 clear days have passed before you can take venlafaxine.

Before you start taking venlafaxine, 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 things that you put on your skin.

Look at the leaflet inside your medicine box for more information about other medicines that can interact with venlafaxine. 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 they contain lactose.

The oral solution contains maltitol, which can be a problem for anyone who has an intolerance to a sugar called fructose.

The oral solution also contains sodium methyl and sodium ethyl parahydroxybenzoate (e219 and e215) which may cause allergic reactions.

There are several companies that manufacture this medicine and the non-active ingredients may vary between products. 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, please note that non-active ingredients used in the production of medicines may sometimes be of animal origin. Ask your pharmacist if you have any questions about the ingredients.

Further information about practical considerations for medicines if you need to avoid animal products can be found on the Vegan Society website.

Taking venlafaxine may make you feel sleepy, dizzy and restless, and could affect your eyesight when you start taking it.

This could affect you if you drive a car, ride a bike, or do anything else that needs a lot of focus.

It is recommended that you stop driving or riding a bike for the first few days or weeks until you know how it affects you.

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

Pregnancy

If you become pregnant while you are on venlafaxine, you should carry on taking it and make an appointment to see your doctor as soon as possible. They can discuss the benefits and risks of continuing venlafaxine 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 venlafaxine during pregnancy at Bumps (Best Use of Medicines in Pregnancy).

Remember that 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 carrying on with venlafaxine has more benefits than risks, you should tell your midwife that you are continuing to take this at your next appointment. 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 venlafaxine.

Some research has shown that taking antidepressants like venlafaxine in the last month of pregnancy can mean there is an increased chance of bleeding after birth. It’s important to let your doctor or midwife know you are taking venlafaxine so they can monitor you after birth. Speak to your doctor if you are worried about this.

Post-natal

Some studies show that antidepressants like venlafaxine if taken in the last five months of pregnancy can cause an increased risk of persistent pulmonary hypertension of the new-born (PPHN). This occurs in the first 24 hours after birth and can make the baby breathe faster and look a bit blue. There are no studies to show that taking venlafaxine increased the risk, but it cannot be rules out. If you’re concerned, speak to your doctor and midwife.

Some newborn babies whose mothers take venlafaxine in the last three months can get symptoms at birth and soon after, like restlessness or feeding difficulties. Tell your midwife if you are taking venlafaxine, so that they can help if the baby has any symptoms after birth.

Breastfeeding

Venlafaxine is passed to the baby in breastmilk in small amounts.

If your baby was born early, then breastfeeding while you are taking venlafaxine may not be recommended. Talk to your midwife and doctor about feeing options.

If you breastfeed while taking venlafaxine, seek urgent medical advice if your baby becomes restless, very sleepy or has feeding problems.

Sex

Venlafaxine can have side effects that might affect your sex life. These include:

problems getting an erection and ejaculating
a painful erection that lasts for a long time (priapism). Go to the hospital for treatment if this lasts longer than 2 hours.
problems with your period
difficulty reaching orgasm
reduced genital sensation
lower sex-drive

Untreated depression or anxiety can have a negative effect on your sex life, so if venlafaxine 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.

There is some evidence that suggests some symptoms, like reduced genital sensation, might continue after you stop taking your medication. This is sometimes called PSSD (post-SSRI sexual dysfunction). Talk to your doctor if you are worried about this.

Fertility

There is no evidence to suggest that venlafaxine will affect your fertility. Talk to your doctor about your venlafaxine if you are trying to get pregnant or planning a family.

Venlafaxine is not a banned substance in sport. However, it can produce a false positive test for phencyclidine and amphetamine. Talk to your doctor about this if it is a problem for you.

Most people play sports as normal while taking venlafaxine, but if venlafaxine affects your concentration, eyesight or co-ordination, then you may want to wait to see if those effects go away before playing sports that need a lot of focus. If you have any concerns, discuss this with your doctor.

Venlafaxine may affect your concentration, make you feel tired or give you blurred eyesight.

Ideally it is best not to take venlafaxine for the first time just before your exams.

It is 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 venlafaxine

You should talk to your doctor about any future exams if you are starting venlafaxine. 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 venlafaxine to improve your motivation and ability to study.

Most people take exams as normal while taking venlafaxine, 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).

Uses, warnings, safety and side effects

Taking venlafaxine

Your doctor will advise you on how long it is best to keep taking your medication. This may vary depending on what you’re taking it for and how many times you’ve been unwell.

If you are prescribed venlafaxine for low mood or depression, it is recommended that you take it for at least six months after you feel well again. This means that most people take it for at least seven to nine months. Research has shown that stopping it sooner, or immediately after you start to feel better, increases the risk of your low mood returning.

If you have had low mood or depression more than once, or if there is a higher risk of you becoming unwell again, your doctor may advise you to continue venlafaxine for at least two years after you feel well again.

If you are prescribed venlafaxine for anxiety, it is recommended that you take venlafaxine for at least one year after you feel well again. Research has shown that stopping it sooner, or immediately after you start to feel better, increases the risk of your symptoms returning.

You will usually take it once a day if you take the modified-release or prolonged-release tablets or capsules, or twice a day if it is the plain tablets.

Your doctor will usually start you with a low dose and gradually increase it to a dose that is effective for you. This may take several weeks but helps to reduce or avoid any side-effects you could get.

Choose a time of the day to take venlafaxine that you can always remember. As venlafaxine should be taken with food, this could be a mealtime or when you have a snack.

Take venlafaxine with food.

Swallow the tablet whole with a glass of water – it tastes bitter if you chew it.

If you find it difficult to take it more than once a day, ask your doctor about the long-acting tablets or capsules because they only need to be taken once a day.

Swallow the long-acting tablets or capsules whole with a drink of water – they are specially made to release the medicine over a few hours into your body and should not be broken, crushed or chewed.

Some parts of the long-acting capsules do not get absorbed into the body and pass straight through. You might see small white balls or granules in your poo. This is not a problem.

If you remember later during the day, take it as soon as possible. However, if this is more than six hours after the dose should be taken, it is usually better to miss the dose and just start again at the next dose.

If you forget to take it by the next dose, just start again with the next dose. Do not try and catch up by taking a double dose.

If you forget to take it for a few days, you may start getting withdrawal symptoms. Sometimes you might experience these symptoms after missing just one dose. These should improve quickly after you start taking venlafaxine again. If they do not, seek advice from your doctor or pharmacist.

If you regularly forget to take it every day, your medicine may not work as well and it could increase the risk of you becoming unwell again.

Do not stop taking venlafaxine suddenly.

Stopping venlafaxine quickly, or reducing the dose too much at once, may cause discontinuation or withdrawal symptoms. These symptoms are more likely to occur with venlafaxine, and may occur after just missing one or two doses.

If you have been taking venlafaxine regularly for more than one to two months, it is recommended that they are stopped gradually (ideally over at least four weeks).

Some people find that very small dose reductions are needed when reducing and stopping this medicine. It maybe that switching to a liquid form can help if you are experiencing difficulties.

Discuss stopping your medication with your doctor. If you have important events coming up or are going through a period of life which is very demanding, it might not be the best time to stop your medication. Planning and support are important to stopping your antidepressant medication successfully.

Antidepressants are not addictive, but if stopped suddenly they can cause discontinuation or withdrawal symptoms. These are caused by the receptors and levels of chemical transmitters in your brain readjusting after you reduce or stop your medication (and can also occur if you miss doses of medication).

Some of the symptoms you get may be like symptoms you had when you were unwell, so understandably, you might may you feel anxious or upset that your illness could be returning.

If you experience symptoms immediately or soon after stopping medication (days rather than weeks), this is usually a withdrawal symptom caused by your body adjusting to not having the medication anymore. If the symptoms start after a month or more after stopping your medicine, this might be a sign that you are becoming unwell again.

Withdrawal symptoms usually start within a few days of stopping (or sometimes reducing) your medication. A wide range of symptoms have been reported. You may experience a few or a range of these:

dizziness and/or feeling unsteady
headaches
numbness or tingling in hands or feet
sleep disturbances (vivid dreams, nightmares, not being able to sleep)
electric shock-like feelings in the head, spine, arms, legs or hands
feeling anxious, agitated or irritable and/or restless
confused or disorientated and reduced concentration
poor appetite, feeling or being sick or having diarrhoea (loose poo)
sweating or shaking
feeling emotional, low mood and tearful
flu-like symptoms/muscle aches and pains
tinnitus (ringing in your ears)
problems with your eyes, or fluttering/pounding heartbeat (these are not as common as the other symptoms listed above)

It is not possible to predict if you will experience withdrawal symptoms, or how bad they will be if you do experience them, but studies report about half of people may get them. The risk appears to be higher if:

you have been taking your medication for six to eight weeks and you stop taking it suddenly
you are a child or young person
you experienced an increase in anxiety symptoms when you started medication
you have experienced withdrawal symptoms with another antidepressant before

If you do experience symptoms, they are usually mild and don’t last long (two to three weeks for most people), but for a few these could be severe enough to make you feel very unwell and last longer (two to three months or more. Arrange an appointment with your doctor to discuss your symptoms and seek advice if you are concerned or unable to tolerate them.

You can stop taking venlafaxine safely with your doctor’s help. Planning a gradual withdrawal together can help to minimise or prevent the withdrawal symptoms you experience.

Warnings and safety

If you have taken more than the dose prescribed by your doctor, contact NHS 111 immediately to ask for advice, or ask a family member or friend to do this for you. This is important even if you don’t feel any different.

NHS 111 can give you advice and direct you to the best place to get more help if you need it.

If you have taken too much medication on purpose, or if after taking this you quickly feel unwell, call 999 or get someone to take you to A&E straight away. This includes:

feeling drowsy or sleepy
changes in your heart rate or breathing
feeling less alert (from sleepiness to coma)
blurred eyesight
seizures or fits
feeling or being sick
high fever, agitation, confusion, trembling, or weird movements of your muscles (these could be signs of serotonin syndrome)

If you need to go to A&E, do not travel alone or drive yourself there. Get your parent, family member or friend to go with you to support you and keep you safe on the way. If someone is not able to drive you there, call for an ambulance. Take your medication with you and tell doctors how much you have taken.

Suicidal thoughts

Depression (and other mental illnesses) can sometimes cause you to have thoughts about hurting yourself or taking your own life. While uncommon, this could also be a side effect of your medicine. These thoughts may happen or get worse in the first few weeks of taking (or stopping) your medication. This can happen to anyone but is more likely to happen if you are under 25 years old.

If you have any thoughts like this, it is important you get urgent help. Contact your doctor immediately for advice and support. This could be your GP or specialist mental health team. If you are able, share how you are feeling with family member or friend as well so they can support you to get help.

If you discussed with your doctor what to do if you get these thoughts and created a safety plan, read this to remind you who to contact for support and what you can do to help you cope.

Read our guide to suicidal feelings

Serious side effects

Venlafaxine can cause rare but serious side effects, including allergic reactions.

Stop taking venlafaxine and go to a hospital straight away if you get any of the following symptoms:

difficulty breathing
an allergic reaction or allergy (including symptoms such as swelling of your face, eyelids, lips, tongue or throat so that you cannot swallow or breathe, or really bad itching of the skin with raised lumps)
a severe skin rash that causes blistering, including your mouth and tongue (these may be signs of a condition known as Stevens Johnson Syndrome, or toxic epidermal necrolysis (TEN))
unexplained muscle pain and tenderness
chest tightness
fast, uneven heartbeat and fainting (this could mean a life-threatening condition called Torsades de Pointes)
any combination of high fever, agitation, confusion, trembling, sweating, diarrhoea (loose poo), fast heartbeat or weird movements of your muscles (this could be serotonin syndrome)
you start having seizures or fits for the first time

Get your parent, family member or friend to take you or go with you to support you and keep you safe on the way. If someone is not able to drive you there, call for an ambulance. Take your medication with you.

Contact your doctor immediately but don't stop taking venlafaxine, if you get any of the following symptoms:

your behaviour changes because you feel very happy, over-excited or aggressive
any unusual bleeding, including blood in your poo
you experience tiredness, confusion and muscle-twitching (you may have a low blood-level of sodium)
yellowing of the skin or whites of the eyes with itching or dark urine (wee) (these may be signs of hepatitis – a problem with your liver)
if fits that you have had in the past happen more often
restlessness, or difficulty sitting or standing still
dizziness, feeling sick or being sick
if your eyesight goes blurred and you have pain in your eyes
rhythmic movements of your muscles that you cannot control, especially in your tongue and mouth
if you get a painful erection (priapism) that lasts more than two hours (this needs to be treated in hospital – go to your nearest emergency department rather than your GP)

If you are unable to contact your doctor, call NHS 111 for urgent advice.

Side effects and your health

Side effects are more common when you first start taking venlafaxine. Many go away as you continue your medicine. If they don’t get better, or if you are worried by them and they are causing you distress, speak to your doctor or pharmacist about them.

Very common side effects (affecting more than one in ten people) include:

feeling sick
feeling dizzy
headache
dry mouth
sweating (including night sweats)
constipation (difficulty pooing)

Common side effects (affecting up to one in ten people) include:

feeling less hungry
confusion, feeling nervous, feeling separated (or detached) from yourself
difficulty having an orgasm, not wanting to have sex or difficulty in getting an erection or ejaculating (coming)
feeling tired, feeling weak, having difficulty sleeping, or unusual dreams
shaking, having pins and needles, increased muscle tone
effects on eyesight like blurred vision, dilated pupils (centre of the eye gets bigger), difficulty of changing eye focus from far to near objects
tinnitus (ringing in the ears)
palpitations, increase in blood pressure, hot flushing, sweating or feeling chills
yawning a lot
vomiting (being sick)
diarrhoea (loose poo)
wanting to wee more often, or having difficulty going for a wee
problems with periods such as more bleeding or irregular bleeding
increased blood cholesterol (seen in blood tests)

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

This list of side effects can look scary. You may not experience any of them, but it’s important to be aware of them so you know what to do if they do happen.

Unless your side effects are very severe or distressing, try to continue taking your medication until you can talk to your doctor. Your doctor can make changes to your medication to help if needed.

Uncommon but important side effects to be aware of include thoughts of harming yourself, thinking about taking your own life or trying to take your own life. This may be a symptom of your illness, including depression, but may be a side effect of medication. If you experience these thoughts, contact your doctor to seek immediate support to keep you safe.

Your doctor will make sure you are monitored carefully for these side effects, and you should decide with your doctor what to do if you experience these feelings while taking venlafaxine. It’s a good idea to write these plans down and keep them somewhere safe.

If you are taking venlafaxine and have not talked about this with your doctor, go back to them and talk it through. You might also want to talk to your parents, family member or friend about it too.

Another uncommon side effect is an increase in your risk of bleeding, including intestinal (stomach or gut) bleeding. Let your doctor know if you vomit blood or develop black or blood-stained poo.

There is no routine monitoring recommended before starting or while you are taking venlafaxine, although your doctor may recommend specific tests, like a blood test, to help them make decisions about your medication.

Occasionally your doctor may check your heart using an electrocardiogram (ECG) before you start taking venlafaxine. This decision will be made depending on your medical history and other medication that you are also prescribed.