Common questions about venlafaxine

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.

It may take1 to 2 weeks before you start to see any changes. But it usually takes between 4 and 6 weeks to feel the full benefits. This is 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.

Antidepressants like venlafaxine help to lift your mood so you feel better. You may notice that you sleep better and feel less anxious. You will hopefully be more relaxed about the things that used to worry you.

Venlafaxine will not change your personality, it will simply help you feel like yourself again.

Do not expect to feel better overnight, though. Some people feel worse during the first few weeks of treatment before they begin to feel better.

For most people, venlafaxine is safe to take for a long time and there are no lasting effects.

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.

Venlafaxine is no better or worse than other antidepressants. However, sometimes, people respond better to one antidepressant than to another. If you are not feeling any better after 6 weeks, talk to your doctor.

Antidepressants, including venlafaxine, are just one of several approaches to treating depression or anxiety.

Other treatments for depression and anxiety include:

• talking therapy (such as cognitive behavioural therapy)
• exercise programmes
• help to get a good night's rest if sleep is a problem
• joining a self-help group
• using relaxation techniques

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.

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:

• problems with getting an erection, or with ejaculating
• some vaginal bleeding
• not reaching 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.

Venlafaxine will not affect any contraception including the combined pill or emergency contraception.

However, if venlafaxine makes you sick (vomit) or have severe diarrhoea for more than 24 hours, your contraception may not protect you from pregnancy. Check the pill packet to find out what to do.

Find out more:

• what to do if you're sick or have diarrhoea when taking the combined pill
• what to do if you're sick or have diarrhoea when taking the progestogen-only pill

Some people cannot 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.

It's an offence to drive a car if your ability to drive safely is affected. It's your responsibility to decide if it's safe to drive.

Talk to your doctor or pharmacist if you're unsure whether it's safe for you to drive while taking venlafaxine. GOV.UK has more information on the law on drugs and driving.

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.

You can eat and drink normally while taking venlafaxine.

Using cannabis while you’re taking venlafaxine can give you a fast heartbeat and make drowsiness worse. This is especially the case in people who have just started taking venlafaxine.

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

Find out more about the side effects of some recreational drugs on the Frank website.