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
Taking venlafaxine originalplayicon listing
Taking Venlafaxine
It felt weird having this tablet inside of you...

If you have any thoughts of suicide, or of other ways of hurting yourself, go straight to a hospital with your medicine.

You need urgent help.

  • Whilst taking venlafaxine, some people may think about hurting themselves or committing suicide. This is more common at the start of treatment than later on.
  • This can happen to anyone, but is more likely to happen if you are less than 25 years old.
  • You must to straight to hospital if you have thoughts of hurting yourself or committing suicide. Take your medicines with you and tell the doctor that you are taking venlafaxine.

Like all medicines venlafaxine has some side effects, and if they happen they can be serious.

Go to a doctor or hospital straight away if you get any of the following symptoms:

  • thoughts of harming or killing yourself
  • chest tightness, wheezing, trouble swallowing or breathing
  • swelling of the face, throat, hands, or feet
  • feeling nervous or anxious, dizziness, throbbing sensations, sudden reddening of the skin and/or a warm feeling
  • a bad rash, itching, or ‘hives’ (raised patches of red or pale skin that often itch)
  • any signs and symptoms of serotonin syndrome which may include restlessness, hallucinations, loss of co-ordination, fast heartbeat, increased body temperature, fast changes in blood pressure, overactive reflexes, diarrhoea, coma, feeling or being sick.
  • For men, a painful erection that lasts for a long time (priapism).
  • Seizures (fits).

Tell your doctor straight away if you get any of the following side-effects:

  • coughing, wheezing, shortness of breath and a high temperature
  • black (tarry) poo, or blood in your poo
  • your skin or the whites of your eyes going yellow, with itching or dark wee (urine), which may be symptoms of problems with your liver (hepatitis)
  • heart problems, such as fast or uneven heartbeat and higher blood pressure
  • eye problems, such as blurred eyesight, or your pupils (black centre of the eye) getting bigger
  • nerve problems, such as dizziness, pins and needles, movement problems, or fits
  • mental health problems, such as hyperactivity and euphoria (feeling unusually overexcited)
  • if you cut or injure yourself, and the bleeding takes a long time to stop
  • allergic reaction or allergy, which may include symptoms such as an itchy skin rash, breathing problems, wheezing, swollen eyelids, face or lips

Young people were more likely than adults to get some side-effects in tests.

Young people aged under 25 were more likely than adults in clinical trials to get the following side-effects from SSRI or SNRI medicines:

  • Thoughts of harming or killing yourself
  • Self-harm
  • Being hostile or aggressive

Some side-effects that do appear should get better after a few days.

Not everyone will experience side effects with venlafaxine. Some of the more common side effects are listed at the bottom of this page. If you are experiencing a problem that might be a side effect, but that is not listed here, please take a look at the patient information leaflet that was in the medicine packet or speak to your pharmacist or doctor. If you think you have a side effect that has not got better within a few days go back to your doctor.

Tell your doctor or pharmacist before you take venlafaxine if you have any of these conditions.

You need to talk to your doctor or pharmacist before you take venlafaxine if any of the following apply to you:

  • eye problems, such as narrow angle glaucoma (increased pressure in the eye)
  • a history of high blood pressure
  • a history of heart problems
  • a history of fits (seizures)
  • a history of low sodium levels in your blood (hyponatraemia)
  • a tendency to develop bruises or a tendency to bleed easily (history of bleeding
  • disorders), or if you are taking other medicines that may increase the risk of bleeding like warfarin (used to prevent blood clots)
  • a history of, or if someone in your family has had, mania or bipolar disorder (feeling over-excited or euphoric)
  • a history of aggressive behaviour
  • if you have ever had thoughts of harming or killing yourself.

Venlafaxine does not mix well with some other medicines and drugs.

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.

Tell your doctor and pharmacist before you take venlafaxine if you are taking any other medicines (including herbal medicines or anything bought at the pharmacy).

Venlafaxine does not mix well with street drugs.

  • Cannabis can make drowsiness worse with venlafaxine.
  • Methadone and heroin can make drowsiness worse with venlafaxine.
  • Taking venlafaxine with cocaine or 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.

Stopping this medicine quickly, or reducing the dose too much at once, may cause uncomfortable symptoms.

You can stop taking it safely by stepping down the dose gradually with your doctor’s help.

Once you start taking venlafaxine, the brain adjusts to having a new level of serotonin and noradrenaline around. If you stop taking venlafaxine suddenly, you could get some withdrawal symptoms.

Venlafaxine is not addictive however, you may get uncomfortable withdrawal symptoms if you stop venlafaxine suddenly, as your body begins to miss it. It is better to agree stopping with a doctor who will reduce you gradually over about 4 weeks.

Some of the withdrawal symptoms you might get include:

  • dizziness, feeling light-headed or having headaches
  • tingling feelings like pins and needles or ‘electric shock’ feelings
  • sleep disturbances (vivid dreams, nightmares, not being able to sleep)
  • feeling anxious, nervous, agitated or confused
  • feeling sick or being sick
  • loose poo (diarrhoea)
  • shaking
  • feeling tired and weak
  • dry mouth and losing your appetite
  • sweating
  • ringing in the ears
  • feeling like you have got flu - muscle weakness and fever.
  • These symptoms should stop after 1-2 weeks for most people, but some people can get them for longer.
  • Most people get mild symptoms, but for some people they can be very intense.
  • Go and speak to your doctor if you have missed a few doses, or have decided to stop taking your medication.
  • When you agree with your doctor to stop the venlafaxine, it is usually best to come off slowly over a number of weeks. This will lower your risk of getting withdrawal symptoms.

If you have any further questions about this you should speak to your doctor or pharmacist.

Some side-effects that do appear should get better after a few days. If they do not, you should go back to your doctor.

Don't stop taking Venlafaxine until you talk to your doctor or you may get withdrawal symptoms as well.

Very common - could affect more than 1 in 10 people

  • Feeling sick
  • Feeling dizzy
  • Headache
  • Dry mouth
  • Sweating (including night sweats)
  • Common - could affect up to 1 in 10 people

    • Feeling less hungry
    • Confusion, feeling nervous, feeling separated (or detached) from yourself
    • Difficulty having an orgasm, not wanting to have sex, difficulty in getting and erection or coming (ejaculating) for men
    • 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 the eye to change its focus from far to near objects
    • Ringing in the ears (tinnitus)
    • Palpitations, increase in blood pressure, hot flushing, sweating or feeling chills
    • Yawning a lot
    • Being sick
    • Constipation (difficulty having a poo) or diarrhoea (loose poo)
    • Wanting to wee more often, or having difficulty going for a wee
    • For women, problems with periods such as more bleeding or irregular bleeding
    • Increased blood cholesterol (seen in blood tests)