Venlafaxine

Venlafaxine should start helping with depression within one to two weeks. It may take four weeks or longer for you to get the full effect. Your doctor will start with a low dose, which they will increase slowly to a dose that is effective for you. This may take several days or weeks.

How people respond to treatment can vary. Sometimes improvement is slow, and you may not feel any different to start with. This can be hard when your mood is low, and if you experience any side effects from your medication you may think you feel worse and not better. If you can, give your medication a chance to work and continue to take it for at least three to four weeks to see if it makes a difference.

Your parents, friends and doctor may notice an improvement in you before you feel it yourself, so it’s a good idea to talk to them.

If you think your medicine has not made any difference to how you feel after three to four weeks, you should go back to your doctor. They might recommend a change in dose or a different medication. However, it can take longer to work for some people than for others, so they may suggest you wait six to eight weeks before deciding.

For anxiety, it may take longer for the benefits to be noticed. It could take up to three months before you feel the full benefit.

For some people, anxiety symptoms briefly increase at the start of treatment, but this should decrease over time. To avoid or minimise this, your doctor will usually start treatment with a low dose and increase this after one to two weeks.

A very common side effect of venlafaxine is a dry mouth. Over a long time, this can increase your risk of developing tooth decay or gum disease. Make sure you brush your teeth well and have regular dental check-ups. Speak to your dentist, doctor or pharmacist about things you can do to help.

Venlafaxine can also cause weight gain or weight loss.

It is not possible to predict how venlafaxine will affect each person before they start taking it. Talk to your doctor or pharmacist if you are concerned about your weight, or changes to your weight, while taking venlafaxine.

You may want to let your family and friends know you are taking venlafaxine so they can support you and help you look out for side effects.

You can feel drowsy in the first few days of taking venlafaxine. This should get better after the first week or two.

Venlafaxine can also disrupt your sleep. You might experience insomnia (difficulty getting to sleep) and vivid dreams or nightmares.

If you have been taking venlafaxine for more than a month and you continue to feel very tired, sleepy or struggle to function during the day, you should go back to your doctor and discuss what changes could be made to help. This may include switching to a different medication.

Alcohol

It may be possible to drink some alcohol while taking venlafaxine but having the two together might make you very sleepy and unsteady on your feet, especially when you first start taking the medication.

During the first few weeks of treatment, it is recommended that you don’t drink alcohol until you know how the medicine affects you.

Drinking alcohol every day, or in large amounts, can make your symptoms worse and may mean you won’t get the maximum benefit from your medication.

Street drugs

Cannabis can make drowsiness worse with venlafaxine.

Cannabis and other drugs may have their own side effects on your mental health, like anxiety or psychosis.

Methadone and heroin can make drowsiness worse with venlafaxine.
Taking venlafaxine with cocaine, 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, so it’s best to be cautious. There is no regulation of street drugs or ‘legal highs’, so even if there are no known issues with the medication you take, the supply you receive might be mixed with other substances that could be dangerous.

Get more advice on our drugs and alcohol guide.

Venlafaxine does not mix well with some other medicines, including herbal remedies. It may affect how they work or could cause more side effects. Always tell the pharmacist that you are taking venlafaxine if you buy any medicines from a pharmacy.

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.

Before you start taking venlafaxine, tell your doctor if you are taking any other medications including things you have bought from a pharmacy or other shop for common illnesses like colds and flu or things that you put on your skin.

Look at the leaflet inside your medicine box for more information about other medicines that can interact with venlafaxine. With some medicines your doctor may need to adjust the dose of your medicines if you take them together. Ask a doctor or pharmacist for more information if you have any questions.

The tablets may not be suitable for you if you have problems eating some sugars or dairy foods, as they contain lactose.

The oral solution contains maltitol, which can be a problem for anyone who has an intolerance to a sugar called fructose.

The oral solution also contains sodium methyl and sodium ethyl parahydroxybenzoate (e219 and e215) which may cause allergic reactions.

There are several companies that manufacture this medicine and the non-active ingredients may vary between products. Always let your pharmacist know if you have any food allergies or intolerances, and always check with them if you’re concerned about any of the ingredients in your medication.

If you need to avoid animal products, please note that non-active ingredients used in the production of medicines may sometimes be of animal origin. Ask your pharmacist if you have any questions about the ingredients.

Further information about practical considerations for medicines if you need to avoid animal products can be found on the Vegan Society website.

Taking venlafaxine may make you feel sleepy, dizzy and restless, and could affect your eyesight when you start taking it.

This could affect you if you drive a car, ride a bike, or do anything else that needs a lot of focus.

It is recommended that you stop driving or riding a bike for the first few days or weeks until you know how it affects you.

Most people drive as normal while taking venlafaxine. If you are worried about this or have any concerns you would like to discuss, speak to your doctor or pharmacist.

Pregnancy

If you become pregnant while you are on venlafaxine, you should carry on taking it and make an appointment to see your doctor as soon as possible. They can discuss the benefits and risks of continuing venlafaxine and help you to make a decision that is best for you and your baby.

They may refer you to a specialist perinatal mental health team to support you with this decision.

You can find out more information about taking venlafaxine during pregnancy at Bumps (Best Use of Medicines in Pregnancy).

Remember that untreated depression or anxiety can also be harmful to you and your developing baby, so decisions about stopping or avoiding medication when you are pregnant need to be discussed carefully with your doctor. If you and your doctor agree that carrying on with venlafaxine has more benefits than risks, you should tell your midwife that you are continuing to take this at your next appointment. If you are planning to get pregnant, it is recommended that you take folic acid while you are trying for a baby and during pregnancy. It is safe to take this together with venlafaxine.

Some research has shown that taking antidepressants like venlafaxine in the last month of pregnancy can mean there is an increased chance of bleeding after birth. It’s important to let your doctor or midwife know you are taking venlafaxine so they can monitor you after birth. Speak to your doctor if you are worried about this.

Post-natal

Some studies show that antidepressants like venlafaxine if taken in the last five months of pregnancy can cause an increased risk of persistent pulmonary hypertension of the new-born (PPHN). This occurs in the first 24 hours after birth and can make the baby breathe faster and look a bit blue. There are no studies to show that taking venlafaxine increased the risk, but it cannot be ruled out. If you’re concerned, speak to your doctor and midwife.

Some newborn babies whose mothers take venlafaxine in the last three months can get symptoms at birth and soon after, like restlessness or feeding difficulties. Tell your midwife if you are taking venlafaxine, so that they can help if the baby has any symptoms after birth.

Breastfeeding

Venlafaxine is passed to the baby in breastmilk in small amounts.

If your baby was born early, then breastfeeding while you are taking venlafaxine may not be recommended. Talk to your midwife and doctor about feeding options.

If you breastfeed while taking venlafaxine, seek urgent medical advice if your baby becomes restless, very sleepy or has feeding problems.

Sex

Venlafaxine can have side effects that might affect your sex life. These include:

• problems getting an erection and ejaculating
• a painful erection that lasts for a long time (priapism). Go to the hospital for treatment if this lasts longer than two hours.
• problems with your period
• difficulty reaching orgasm
• reduced genital sensation
• lower sex-drive

Untreated depression or anxiety can have a negative effect on your sex life, so if venlafaxine helps you to recover, positive effects can include improving your desire, experience and enjoyment of sex as your mood lifts and you become interested in life and relationships again.

There is some evidence that suggests some symptoms, like reduced genital sensation, might continue after you stop taking your medication. This is sometimes called PSSD (post-SSRI sexual dysfunction). Talk to your doctor if you are worried about this.

Fertility

There is no evidence to suggest that venlafaxine will affect your fertility. Talk to your doctor about your venlafaxine if you are trying to get pregnant or planning a family.

Venlafaxine is not a banned substance in sport. However, it can produce a false positive test for phencyclidine and amphetamine. Talk to your doctor about this if it is a problem for you.

Most people play sports as normal while taking venlafaxine, but if venlafaxine affects your concentration, eyesight or co-ordination, then you may want to wait to see if those effects go away before playing sports that need a lot of focus. If you have any concerns, discuss this with your doctor.

Venlafaxine may affect your concentration, make you feel tired or give you blurred eyesight.

Ideally it is best not to take venlafaxine for the first time just before your exams.

It is not possible to predict how the medication will make you feel, and if you do get any side effects, these are more likely to occur when you first start taking venlafaxine

You should talk to your doctor about any future exams if you are starting venlafaxine. You might decide together to delay starting it until you have done them.

If they are more than a month away, however, you might find that it is better to start venlafaxine to improve your motivation and ability to study.

Most people take exams as normal while taking venlafaxine, but if you have any concerns, discuss this with your doctor.