Venlafaxine

You will need to take venlafaxine for several months after you feel better, otherwise your symptoms can come back. For depression this might be for six 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.

If you stop taking the venlafaxine too soon, there is more chance that your 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.

Your dose will need to be reduced gradually to reduce the chance of withdrawal effects when it is stopped (unless you are already on the lowest dose).

You will get most benefit from your venlafaxine if you take it every day at the dose prescribed by your doctor.

Make sure that you know your dose. If it is not written on the label, check with your pharmacist or doctor.

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).

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 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 take a double dose.

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.

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, but you may get uncomfortable withdrawal symptoms if you stop taking it suddenly, as your body begins to miss it. It is better to agree stopping with a doctor who will reduce your dose gradually over several 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
• diarrhoea (loose poo)
• 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 one to two 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 few weeks. This will lower your risk of getting withdrawal symptoms.

If you have taken more venlafaxine than the dosage recommended by the doctor who prescribed it to you, you must get medical help immediately – even if you do not feel any different.

While taking venlafaxine, some people may think about hurting themselves or taking their own lives. 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, or serotonin syndrome (symptoms of this include a high fever, agitation, confusion, trembling, or weird movements of your muscles). 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, but 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.

Venlafaxine may affect the developing baby during pregnancy. If you are trying for a baby or become pregnant while taking venlafaxine, you should speak with your doctor as soon as possible to discuss options and alternatives.  

If you have taken more venlafaxine than the dosage recommended by the doctor who prescribed it to you, you must get medical help immediately – 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 heartbeat
• feeling less alert (from sleepiness to coma)
• blurred eyesight
• seizures (fits)
• being sick
• high fever, agitation, confusion, trembling, or weird movements of your muscles (these could be signs of serotonin syndrome)

While taking venlafaxine, some people may think about hurting themselves or taking their own lives. This is more common at the start of treatment than later. 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 taking your own life. Take your medicines with you and tell the doctor that you are taking venlafaxine.

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

• thoughts of harming yourself or taking your own life
• 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, overactive reflexes, diarrhoea, coma, feeling or being sick
• a painful erection that lasts for a long time (priapism)
• seizures (fits)

Tell your doctor straight away if you develop any of the following:

• 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 urine (wee), which may be symptoms of hepatitis (a problem with your liver)
• 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
• 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). Your doctor will stop your treatment in these cases
• allergic reaction or allergy, which may include symptoms such as an itchy skin rash, breathing problems, wheezing, swollen eyelids, face or lips
• rhythmic movements of your muscles that you cannot control, especially in your tongue and mouth

Like all medicines, venlafaxine can cause side effects, which can be serious.

In clinical trials, young people aged under 25 were more likely than adults to get the following side effects from SSRI or SNRI medicines:

• thoughts of self-harm and/or taking their own lives
• self-harm
• hostile or aggressive behaviour

Not everyone will experience side effects with venlafaxine. If you do experience side effects, some of them should disappear or get better within a few days or weeks.

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, for people who have a penis, 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)

If you are experiencing a problem that might be a side effect, but that is not listed here, please 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.