- It usually takes 4 to 6 weeks for venlafaxine to work.
- Side effects such as feeling sick, headaches, sweating, and dry mouth are common. They are usually mild and go away after a couple of weeks.
- If you and your doctor decide to take you off venlafaxine, your doctor will probably recommend reducing your dose gradually to help prevent extra side effects.
- Venlafaxine has lots of different brand names including Efexor XL.
Venlafaxine can be taken by adults for depression, anxiety and panic attacks.
Check with your doctor before starting to take venlafaxine if you:
- have had an allergic reaction to venlafaxine or any other medicines in the past
- have a heart problem - as venlafaxine can speed up or change your heartbeat
- are trying to become pregnant, are already pregnant or you are breastfeeding
- have an eye problem called glaucoma because venlafaxine can increase the pressure in your eye
- have epilepsy or are having electroconvulsive treatment - venlafaxine may increase your risk of having a seizure
If you have diabetes, venlafaxine can make it more difficult to keep your blood sugar stable. Monitor your blood sugar more often for the first few weeks of treatment with venlafaxine and adjust your diabetes treatment if necessary.
Take venlafaxine once or twice a day as recommended by your doctor. It's best to take venlafaxine with food so it doesn't make you feel sick.
How much to take
The usual starting dose of venlafaxine is 75mg a day. This might be gradually increased to a maximum dose of 375mg.
If you have problems with your liver or kidneys your doctor might prescribe a lower dose.
Venlafaxine tablets and capsules can be either immediate release or extended release. How you take them depends on the type you've been prescribed.
Immediate release tablets release the venlafaxine into your system as soon as you swallow them. You will usually take 37.5mg immediate release tablets twice a day, once in the morning and once in the evening.
Extended release tablets and capsules are released into your system gradually. You will usually take 75mg extended release tablets or capsules once a day. You can choose to take them at any time as long as you stick to the same time every day. If you have trouble sleeping, it's best to take it in the morning.
What if I forget to take it?
If you occasionally forget to take a dose, don't worry. Take your next dose at the usual time. 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?
The amount of venlafaxine that can lead to an overdose varies from person to person.
Call your doctor straight away if:
You've taken too much venlafaxine by accident and experience symptoms such as:
- feeling sleepy
- being sick (vomiting)
- a racing heart
If you need to go to a hospital accident and emergency (A&E) department, do not drive yourself - get someone else to drive you or call for an ambulance.
Take the venlafaxine packet, or the leaflet inside it, plus any remaining medicine with you.
Like all medicines, venlafaxine can cause side effects in some people, but many people have no side effects or only minor ones. Some of the common side effects of venlafaxine will gradually improve as your body gets used to it.
Common side effects
These side effects happen in more than 1 in 100 people. Keep taking the medicine, but tell your doctor or pharmacist if these side effects bother you or don't go away:
- feeling sick
- dry mouth
- trouble sleeping
- feeling dizzy
- feeling sleepy
Serious side effects
It is not common, but some people (less than 1 in 100) may have serious side effects when taking venlafaxine.
Go to A&E immediately if you get:
- chest pain or pressure, shortness of breath, or a fast or irregular heart beat
- severe dizziness or passing out
- any bleeding that is very bad or that you cannot stop such as cuts or nose bleeds that don't stop within 10 minutes
Call your doctor straight away if experience:
- constant headaches, long-lasting confusion or weakness, or frequent muscle cramps can all be signs of low sodium levels in your blood - in severe cases low sodium levels can lead to seizures
- feelings of euphoria, excessive enthusiasm or excitement, or a feeling of restlessness that means you can't sit or stand still
- unexplained muscle pain or weakness
- yellow skin or the whites of your eyes turn yellow - this can be a sign of liver problems
- any changes in your eyesight, like blurred vision or dilated pupils
- vomiting blood or dark vomit, coughing up blood, blood in your pee, black or red poo - these can be signs of bleeding from the gut
- bleeding from the gums or bruises that appear without a reason or that get bigger
- thoughts about harming yourself or ending your life
Book an appointment with your doctor if you experience:
- weight gain or weight loss without trying
- changes in your periods such as heavy bleeding, spotting, or bleeding between periods
Serious allergic reaction
In rare cases, it's possible to have a serious allergic reaction (anaphylaxis) to venlafaxine.
Contact a doctor straight away if:
- you get a skin rash that may include itchy, red, swollen, blistered or peeling skin
- you're wheezing
- you get tightness in the chest or throat
- you have trouble breathing or talking
- your mouth, face, lips, tongue or throat start swelling
These are warning signs of a serious allergic reaction. A serious allergic reaction is an emergency.
These are not all the side effects of venlafaxine. For a full list see the leaflet inside your medicines packet.
You can report any suspected side effect to the UK safety scheme.
What to do about:
- feeling sick - try taking venlafaxine with or after food. It may also help if you avoid rich or spicy food. If it carries on, tell your doctor.
- headaches - make sure you rest and drink plenty of fluids. Do not drink too much alcohol. Ask your pharmacist to recommend a painkiller. Headaches should usually go away after the first week of taking venlafaxine. Talk to your doctor if they last longer than a week or are severe.
- a dry mouth - chew sugar-free gum or sugar-free sweets.
- feeling dizzy - if venlafaxine makes you feel dizzy when you stand up, try getting up very slowly or stay sitting down until you feel better. If you begin to feel dizzy, lie down so that you don't faint, then sit until you feel better. Do not drive or use tools or machines if you feel dizzy or if you just feel a bit shaky.
- feeling sleepy - do not drive or use tools or machinery if you're feeling this way. Cut down the amount of alcohol you drink as this will make you feel more tired. If this symptom does not go away after a week or 2, ask your doctor for advice.
- being unable to sleep - take venlafaxine first thing in the morning.
- constipation - get more fibre into your diet such as fresh fruit and vegetables and cereals, and drink plenty of water. Try to exercise, for example, by going for a daily walk or run. If this doesn't help, talk to your pharmacist or doctor. Watch this short video about how to treat constipation.
It's important for you and your baby that you stay well during your pregnancy. If you become pregnant while taking venlafaxine speak to your doctor. Do not stop taking your medicine unless your doctor tells you to.
Venlafaxine 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 venlafaxine 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.
For more information about how venlafaxine can affect you and your baby during pregnancy, visit the Best Use of Medicines in Pregnancy (BUMPS) website.
Venlafaxine and breastfeeding
If your doctor or health visitor says your baby is healthy, venlafaxine can be used during breastfeeding. It has been used in breastfeeding mothers usually without any problems.
Venlafaxine passes into breast milk in small amounts. It has been linked with side-effects in very few breastfed babies.
It is important to continue taking venlafaxine 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 if you have any other concerns about your baby, then talk to your health visitor or doctor as soon as possible.
Tell your doctor if you're:
- trying to get pregnant
Some medicines and venlafaxine can interfere with each other and increase the chances of you having side effects.
Tell your doctor if you're taking these medicines before you start venlafaxine:
- any medicines that affect your heartbeat - as venlafaxine can speed up or change your heartbeat.
- any other medicines for depression. Some rarely used antidepressants can interact with venlafaxine to cause very high blood pressure even when they have been stopped for a few weeks.
Mixing venlafaxine with herbal remedies and supplements
Do not take the herbal remedy for depression, St John's wort, while you are being treated with venlafaxine as it will increase your risk of side effects.
Tell your doctor or pharmacist if you are taking any other medicines, including herbal remedies, vitamins or supplements.
How does venlafaxine work?
Venlafaxine is one of a group of antidepressants called serotonin and noradrenaline reuptake inhibitors, or SNRIs. These medicines are thought to work by increasing the levels of mood-enhancing chemicals called serotonin and noradrenaline in the brain.
When will I feel better?
You may see an improvement in your symptoms after a week although it usually takes between 4 and 6 weeks before you feel the full benefits. That's because it takes around a week for venlafaxine levels to build up in your body, and then a few weeks longer for your body to adapt and get used to it.
Do not stop taking venlafaxine just because you feel it is not helping your symptoms. Give the medicine at least 6 weeks to work.
How will it make me feel?
Antidepressants like venlafaxine help to jump start your mood so you feel better. You may notice that you sleep better and get on with people more easily because you're less anxious. You will hopefully take little things that used to worry you in your stride.
Venlafaxine won't change your personality or make you feel really happy. It will simply help you feel like yourself again.
Don't expect to feel better overnight, though. Some people feel worse during the first few weeks of treatment before they begin to feel better.
How long will I take it for?
Once you're feeling better it's likely that you will continue to take venlafaxine for several more months. Most doctors recommend that you take antidepressants for 6 months to 1 year after you no longer feel depressed. Stopping before that time can make depression come back.
Is it safe to take it for a long time?
For most people, venlafaxine is safe to take for a long time.
A few people may get sexual side effects, such as problems getting an erection or a lower sex drive. In some cases these can continue even after stopping the medicine. Speak to your doctor if you are worried.
Otherwise there don’t seem to be any lasting harmful effects from taking venlafaxine for many months and years.
How do I come off venlafaxine?
If you've been feeling better for 6 months or more, your doctor may suggest coming off venlafaxine.
Your doctor will probably recommend reducing your dose gradually over several weeks - or longer, if you have been taking venlafaxine for a long time.
This is to help prevent any extra side effects you might get as a reaction to coming off the medicine. These include:
- feeling sick
- numbness or tingling in the hands or feet
- trouble sleeping
- feeling agitated or anxious
Do not stop taking venlafaxine suddenly, or without talking to your doctor first.
Is venlafaxine better than other antidepressants?
Venlafaxine isn't any better or worse than other antidepressants. However, sometimes people respond better to one antidepressant than to another. If you aren't feeling any better after 6 weeks, talk to your doctor.
Are there other treatments that will help?
Antidepressants, including venlafaxine, are just one of several approaches to treating depression or anxiety.
Other potential treatments for depression include:
- talking therapy (such as cognitive behavioural therapy)
- exercise programmes
- help to get a good night's rest if sleep is a problem
Other potential treatments for anxiety include:
- talking therapy (such as cognitive behavioural therapy)
- joining a self-help group
- using relaxation techniques
Choosing a treatment that's most suitable for you depends on:
- how long you've had depression or anxiety and your symptoms
- whether previous treatment has worked
- how likely you are to stick with your treatment
- the potential side effects
- your preferences and priorities
If you're interested in any of these treatments, talk to your doctor.
Will it affect my fertility?
There's no firm evidence to suggest that taking venlafaxine will reduce fertility in men, but it may interfere with the menstrual cycle in women.
Speak to a pharmacist or your doctor if you're trying to get pregnant. They may want to review your treatment.
Is there any food or drink I need to avoid?
You can eat and drink normally while taking venlafaxine.
Will I gain or lose weight?
Venlafaxine can make you feel less hungry than usual, so you may lose weight when you start taking it. Some people might find they gain weight.
If you start to have problems with your weight while taking venlafaxine, talk to your doctor or pharmacist.
Will it affect my sex life?
The good effects of venlafaxine may, after a while, improve your sex life as your mood lifts and you become interested in life and relationships again.
Some of the possible negative effects include:
- men might have problems with getting an erection, or with ejaculating
- women might have some vaginal bleeding
- both men and women might find they don't reach orgasm the same way as before
- you may have a lower sex drive
Sexual side effects usually pass after the first couple of weeks. However, very rarely, they can be long lasting and may not get better even after stopping the medicine.
If these happen and are a problem for you, go back to your doctor to see if there's another treatment you can try.
Will it affect my contraception?
Can I drive or ride a bike?
Some people can't concentrate properly while they're taking venlafaxine. It might be best to stop driving and cycling for the first few days of treatment until you know how this medicine makes you feel.
Can I drink alcohol with it?
You can drink alcohol while taking venlafaxine but it may make you feel sleepy. It might be best to stop drinking alcohol during the first few days of treatment until you see how this medicine affects you.
Will recreational drugs affect it?
Cannabis with venlafaxine can give you a fast heartbeat. Cannabis can also make drowsiness worse with venlafaxine, especially in people who have just started taking it.
Methadone can make sleepiness worse with venlafaxine. It can be potentially dangerous to take venlafaxine with:
- stimulants like MDMA (ecstasy) or cocaine
- hallucinogens like LSD
- novel psychoactive substances (which used to be known as legal highs) like mephedrone
Venlafaxine has not been properly tested with recreational drugs. Talk to your doctor if you think you might take any while taking venlafaxine.