Venlafaxine: uses, benefits and side effects

As an SNRI, venlafaxine increase the concentration of the neurotransmitters serotonin and norepinephrine in the brain and body. Serotonin influences mood, sleep and appetite, while norepinephrine (also known as noradrenaline) is used in the body’s ‘fight or flight’ response.

It usually takes four to six weeks for the full effects of venlafaxine to kick in.

Venlafaxine comes as modified release tablets and normal tablets, as well as modified release capsules and normal capsules. The available strengths for each of these are 37.5mg, 75mg, 150mg and 225mg.

Most people who take venlafaxine start on a dose of 75mg a day. This can increase gradually to the maximum dose of 375mg a day.

The dose you will be given is the one your GP feels will initially work best for your particular situation. If you have any questions about your venlafaxine dosage, be sure to ask your GP or pharmacist.

Take venlafaxine once a day or twice a day - whichever your GP directed you to do. Ideally, you should have venlafaxine with food so that it doesn’t make you feel sick.

If you think the venlafaxine isn’t working or you are experiencing a prolonged period of side effects, do not give up the medication suddenly. Doing so can cause a range of withdrawal symptoms. Speak to your GP or pharmacist if you have concerns about the effectiveness of your venlafaxine dose.

As an SNRI, venlafaxine has fewer unwanted side effects than other types of antidepressants. However, common side effects happen in more than 1 in 100 people.

Tell your GP if you are experiencing:

Serious side effects of venlafaxine are less common and happen in less than 1 in 100 people.

Get in touch with your GP as soon as you can if you develop:

It’s worth noting that this is not a comprehensive list of venlafaxine side effects. For a full list check your patient information leaflet, or speak to your GP or pharmacist for more information.

The active ingredient in venlafaxine can interact with a number of other medicines.

Do not take venlafaxine with the following medicines:

Taken alongside venlafaxine, the following medicines may trigger side effects:

Before starting a course of venlafaxine, be sure to let your GP know if you are already taking any medicines, vitamins or supplements. A full list of interactions with venlafaxine can be found on the NICE website.

There are certain instances when it may not be suitable to take venlafaxine.

Speak to your GP if you:

Your GP will weigh up the situation and suggest treatment that best meets your situation.

If you are pregnant or are planning a pregnancy, it’s important to keep your GP in the loop. Although generally safe for pregnant women, venlafaxine can has been linked to a very small increased risk of problems for unborn babies.

If you are suffering from depression, anxiety or panic disorder, it’s important to treat your condition during pregnancy. That’s why it’s vital that you consult your GP about the treatment - they will advise you of the risks and together you can make the best decision for you and your baby.

Venlafaxine is generally safe to use if you’re breastfeeding, though small amounts can pass into the breastmilk. If you’re taking venlafaxine while breastfeeding and notice that your baby is unwell, speak to your health visitor or GP.