HeadMeds gives young people in the United Kingdom general information about medication. HeadMeds does not give you medical advice. Please talk to your Doctor or anyone else who is supporting you about your own situation because everyone is different. Please read more important details about our site.

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Venlafaxine

Return to Venlafaxine overview
  1. Use and Action
  2. Warnings and side effects
  3. Sex, drink, weight and everything else
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Taking Melatonin, Fluoxetine and Sertraline
I think it’s really important to understand that medications aren’t a ‘one size fits all’ type of thing.

Venlafaxine can be used to treat the following conditions

Headmeds fills the medicines information gaps for young people - things you might want to know about meds like will it affect my sex life? Can I still study?  Can I drink?
Headmeds does not give medical advice so this is just general information.
Each medicine has a balance of good and bad effects, and each person gets their own individual effects.
You might want to know just one thing about your medicine, but on each page we have given you the ‘safety headlines’. Please read them as they are important.

We have included lots of information about each medicine - but if you want all the details, please look at the patient information leaflet - which is inside every pack. These leaflets are also at www.medicines.org.uk - where there will be the most up-to-date information. Please be aware that the leaflets will only refer to the licensed use for your medicine. The leaflet will not mention any off label use - this includes off label conditions and also off label age groups.

Safety headlines

  • If you have taken more venlafaxine than it said on the label, you must see a doctor quickly - even if you do not feel any different.
  • Venlafaxine can make some people think about hurting themselves or committing suicide. You must go straight to hospital with your tablets if you have any of these thoughts.
  • Venlafaxine can also cause other rare, but serious side-effects: allergic reactions (difficulty breathing, swelling of your face or throat, itching skin lumps), severe rash, unexplained muscle pain and tenderness, chest tightness, difficulty breathing, serotonin syndrome and neuroleptic malignant syndrome (see “Warnings and Side Effects” section for descriptions of these two side effects). Go to a hospital if you get any of these symptoms, and take your medicine with you.
  • Do not take venlafaxine if you have taken a monoamine oxidase inhibitor antidepressant (MAOI) like moclobemide, phenelzine, isocarboxazid or tranylcypromine in the last 14 days.
  • Stopping venlafaxine suddenly can cause serious side-effects - go to your doctor if you want to stop, or if you are having these effects. Venlafaxine is not addictive, however stopping it suddenly can cause problems such as: feeling dizzy or shaky, sleep problems (including difficulty sleeping and intense dreams), feeling irritable or anxious, feeling or being sick, and headaches - go to your doctor if you want to stop, or if you are having these effects.
  • You might feel sleepy or restless, and may not be able to see properly, in the first few days after taking venlafaxine – do not drive a car, ride a bike or operate machines until you see how this affects you.
  • If you are pregnant, or thinking of becoming pregnant, please read the pregnancy section (see “Sex, drink, weight and everything else”) because venlafaxine may affect the developing baby.

Basic details

Venlafaxine has been used for a number of conditions.

  • Depression (low mood)
  • Generalised anxiety disorder
  • Social anxiety disorder
  • Panic disorder

How does venlafaxine work?

Venlafaxine is a type of antidepressant called a selective serotonin and noradrenaline reuptake inhibitor (SNRI). Serotonin and noradrenaline are neurotransmitters (chemicals that relay signals between the cells in your brain). In illnesses such as depression, there is less serotonin and noradrenaline available to relay signals - both are important in areas of the brain that control mood and thinking. Venlafaxine works by blocking the way serotonin and noradrenaline are removed from between brain cells. By preventing serotonin and noradrenaline from being taken away from the area between the brain cells more is available and this helps to boost the signal and the symptoms of depression and low mood get better. At high doses venlafaxine also blocks the way dopamine is removed.

Are the tablets and capsules suitable for everyone?

  • Venlafaxine long-acting capsules contain gelatine and may not be suitable if you don’t eat meat.
  • Venlafaxine tablets and long-acting tablets may not be suitable for you if you have problems eating some sugars or dairy (milk-based) foods, as they contain lactose.
  • Some venlafaxine tablets contain a colour called sunset yellow (also called E110) that might cause an allergic reaction in some people. If you are allergic to aspirin, you are more likely to be allergic to this colour. So, talk to your pharmacist or doctor if you are allergic to aspirin or any food additives.

You should take venlafaxine as agreed with your doctor.

  • You will get most benefit from your venlafaxine if you take it every day.
  • Make sure that you know your dose. If it is not written on the label, check it with your pharmacist or doctor.
  • You will usually take it once a day (if it is the modified release or prolonged release) or twice a day (if it is the plain tablets).
  • You will usually start with a low dose that your doctor will gradually increase to a dose that is effective for you. This may take several weeks.
  • 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 particular 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 have 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.

What should I do if I forget to take a dose of venlafaxine?

What to do if you miss a dose:

  • If you remember later during the day, take it as soon as possible. However, if this is more than 6 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 take a double dose.

What might happen?

  • If you forget to take your tablets for a few days, you may start getting your old symptoms back, or get withdrawal symptoms (feeling dizzy or shaky, sleep problems (including difficulty sleeping and intense dreams), feeling irritable or anxious, feeling or being sick, and headaches). If this happens you should talk to your doctor about it.

You must go to A&E if you take too much.

What to do if you take too much:

  • If you have taken more venlafaxine than it said on the label, you must get help quickly - 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 to go with you, if you can, just in case you feel ill on the way.

You might get any of the following signs:

  • fast heart beat
  • feeling less alert (from sleepiness to coma)
  • blurred eyesight
  • fits (seizures)
  • being sick

You are also at risk of getting Serotonin syndrome. This is when you can get a high fever, agitation, confusion, trembling, or weird movements of your muscles. This is rare, but you should watch out for it.

How long will it take for venlafaxine to start working?

  • Antidepressants like venlafaxine can start to work on depression within the first two weeks of treatment, and the improvement continues over the following few weeks. It may take four weeks or longer for you to get the full effect.
  • For anxiety, antidepressants like venlafaxine can take slightly longer to work. For some people, anxiety briefly increases at the start of treatment, but the anxiety does decrease with continued treatment.
  • Some side effects of venlafaxine tend to happen at the start of treatment, but go away after a few days, such as feeling or being sick (nausea or vomiting).
  • To get the best effect, you need to take your venlafaxine every day and give it a chance to work for you.
  • Your doctor will start with a low dose that increases slowly to a dose that is effective for you. This may take several days or weeks.
  • You will need to take venlafaxine for several months after you feel better - otherwise your symptoms can come back.
  • Keep taking venlafaxine as you get better, which can take a few months, and then keep taking it. Your doctor will advise you how long as depends on what you are taking the venafaxine for. For depression it might be 6 months but for other conditions such as generalised anxiety disorder it might be up to 18 months.
  • If your illness has come back, then you might be advised to keep taking venlafaxine for longer than this.
  • This will help keep you well. If you stop taking the venlafaxine too soon, there is more chance that your mental health symptoms will come back.
  • Discuss with your doctor how long you should take venlafaxine for.
  • If you have bipolar disorder, it is likely that the doctor will advise for the venlafaxine to be stopped sooner. This is because, in bipolar disorder, there is a risk of your mood becoming too high if an antidepressant is used for too long.
  • See your doctor if you want to stop venlafaxine, to make sure it is not too soon to stop it.
  • Also, the venlafaxine dose will need to be reduced gradually to reduce the chance of side effects when it is stopped (unless you are already on the lowest dose).

Reference sources