Paroxetine

How it works

What does paroxetine do?

Paroxetine is a type of antidepressant called a selective serotonin reuptake inhibitor (SSRI).

Research suggests that depression or low mood is more likely to occur when the brain doesn’t have enough serotonin.

Serotonin (also called '5HT') is a naturally-occurring chemical messenger (or “neurotransmitter”) that has an important role in areas of the brain that control mood and thinking.

Selective serotonin reuptake inhibitors (SSRIs) - like paroxetine - are thought to work by increasing levels of serotonin in the brain. They do this by blocking the recycling of released serotonin back into the nerve endings.

Paroxetine is often prescribed alongside a talking therapy.

How long does paroxetine take to start working?

It takes one to two weeks for paroxetine to start helping, and it could take some weeks or months to get its full effect. We believe this is due to adaptive changes needing to take place in the brain.

Your doctor might start you on a low dose and then increase it slowly over two to four weeks to your full dose.

How long will I need to take paroxetine?

You and your doctor should talk about how long you need to take paroxetine before you start your treatment.

Your doctor needs to know if...

You need to talk to your doctor or pharmacist before starting treatment with paroxetine if you have any of the following:

• eye problems, such as glaucoma (increased pressure in the eye)
• low sodium levels
• diabetes (high sugar levels in your blood)
• a tendency to develop bruises or to bleed easily (bleeding disorders)
• mania
• kidney or liver problems
• heart problems
• seizures (fits)
• thoughts of harming yourself or taking your life
• treatment with electroconvulsive therapy (ECT)

Some manufacturers include lactose and Sunset Yellow in their tablets. Talk to your pharmacist if you have any concerns about the ingredients.

The liquid medicine contains sorbitol (E420). If you have been told by your doctor that you have an intolerance to fructose, contact your doctor before taking Seroxat suspension.

The oral suspension also contains methyl parahydroxybenzoate (E218), propyl parahydroxybenzoate (E216) and sunset yellow FCF (E110), all of which can cause allergic reactions.

Taking paroxetine

You should only take paroxetine as agreed with your doctor.

You will get the best effect from paroxetine 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.

Choose a time each morning that you can always remember to take your paroxetine. This could be with breakfast, or when you brush your teeth.

Take it after food. This helps to prevent feelings of sickness.

Swallow the tablet with a drink of water - if you chew it, it tastes bitter.

What if I miss a dose?

If you remember later during the day, take it as soon as possible.

You may find it difficult to sleep if you take it towards bedtime.

If you forget to take it by the time of your next dose, just take the next dose.

Do not take a double dose. 

What will happen if I forget to take my paroxetine?

If you forget to take it for a few days, you may start getting withdrawal symptoms. Talk to your doctor if this happens to you.

Stopping the use of paroxetine

Stopping paroxetine quickly, or reducing the dose too much at once, may cause uncomfortable symptoms Paroxetine is well known for more readily causing unpleasant effects if you stop it quickly, but you can stop taking it safely with your doctor’s help.

Once you start taking an SSRI, the brain adjusts to having a new level of serotonin around. If you stop taking the SSRI all at once, the balance starts to change again. You could get some symptoms from the change.

Some of the symptoms you might get include:

• dizziness or headaches
• tingling feelings like pins and needles, or electric shocks, including in the head
• sleep disturbances (vivid dreams, nightmares, not being able to sleep)
• tinnitus (ringing or other noises in the ear)
• feeling anxious, restless, agitated, confused or disorientated
• feeling emotional or irritable
• feeling sick or being sick
• diarrhoea (loose poo)
• shaking
• sweats (including night sweats)
• problems with your eyesight
• a fluttering or pounding heartbeat

These symptoms should go away after two weeks for most people, but some people can get them for a few months.

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.

The information on this page was reviewed by the College of Mental Health Pharmacy in March 2020.

Safety headlines

If you have taken more paroxetine 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 paroxetine, some people may think about hurting themselves or taking their own lives. You must go straight to hospital with your medicine if you have any of these thoughts.

Paroxetine can also cause other serious side effects: allergic reactions (difficulty breathing, swelling of your face or throat, itching skin lumps), and other serious symptoms that you can find here. Go to a hospital if you get any of these symptoms, taking your medicine with you.

Do not take paroxetine if you have taken a monoamine oxidase inhibitor antidepressant (MAOI) like moclobemide, phenelzine, isocarboxazid or tranylcypromine in the last 14 days.

Stopping paroxetine suddenly can cause unpleasant withdrawal effects. Go to your doctor if you want to stop, or if you are having these effects.

You might not be able to concentrate very well, and may feel sleepy, in the first few days after taking paroxetine. Do not drive a car, ride a bike or operate machines until you see how this affects you.

Use good contraception while you are taking paroxetine. If you take paroxetine while you are pregnant, it may affect the developing baby. It can also cause symptoms in newborn babies if you take it at the end of pregnancy. Talk to your doctor or midwife about this and get their help.

When to go to the hospital

If you have taken more paroxetine 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 or family member to go with you in case you feel ill on the way.

You are also at risk of getting serotonin syndrome. Symptoms of this include a high fever, agitation, confusion, trembling, or weird movements of your muscles. This is rare, but you should watch out for it.

If you have any thoughts of taking your own life, or of other ways of hurting yourself, go straight to a hospital with your medicine. This may be a side effect and is especially common in people who are under 18. You must go straight to hospital with your medicine if you have any of these thoughts. You must tell the doctor that you are taking paroxetine. There are other medicines you can take instead.

Stop taking paroxetine and go to a doctor or hospital straight away if you get any of the following symptoms:

• difficulty breathing
• any red or lumpy skin rash and itching
• swelling of your eyelids, face, lips, mouth, tongue or throat so that you cannot swallow or breathe
• feeling lightheaded and weak, collapsing or fainting

Go to a doctor or hospital straight away, but do not stop your paroxetine, if you get any of the following symptoms:

• you have unusual bruising or bleeding, including seeing blood in your vomit (sick) or in your poo
• if you cannot urinate (pee)
• if you have seizures (fits)
• you get a high temperature/fever, agitation, confusion, restlessness, hallucinations, sweating, shivering, a fast heartbeat, trembling or weird jerking muscle movements. These may be signs of a rare condition called serotonin syndrome
• a painful erection that lasts for a long time (priapism)
• red blisters, and skin peeling off large areas of your body

When to see your doctor

Contact your doctor, but do not stop your paroxetine, if you get any of the following symptoms:

• feeling tired, confused and having muscle twitching. You may have a low blood level of sodium
• feeling restless, and not being able to sit still
• if your eyesight goes blurred and you have pain in your eyes
• feeling aggressive

Side effects

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

If you get any side effects not listed here please look at the patient leaflet in the medicine pack.

Do not stop taking the tablets until you talk to your doctor, or you may get withdrawal symptoms as well.

Very common side effects (affecting more than one in ten people) include:

• nausea (feeling sick), which is why you should take paroxetine with food
• decreased sex drive or sexual problems, including difficulty maintaining an erection (staying hard) and difficulty reaching orgasm (coming)

Common side effects (affecting up to one in ten people) include:

• loss of appetite
• higher blood cholesterol (seen in blood tests)  
• weight gain
• finding it difficult to concentrate
• feeling agitated
• insomnia (sleep problems), unusual dreams, or sleepiness
• dizziness and shaking
• headache
• dry mouth
• blurred vision
• feeling very weak
• diarrhoea (loose poo) or constipation (difficulty pooing)
• being sick
• sweating more than usual
• unusual yawning

Particular side effects that are more common in young people under 18 include:

• an increase in thoughts of harming themselves or taking their own lives
• deliberate self-harm
• being hostile, aggressive or unfriendly
• low appetite
• shaking
• excessive sweating
• hyperactivity (having too much energy)
• feeling agitated
• changing emotions and moods, including crying

There are other side effects that you can get when taking this medicine – we have only included the most common ones here.

Please look at the leaflet inside your medicine box, or ask a doctor or pharmacist, if you want to know whether you are getting a side effect from your medicine.

If you do get a side effect, please think about reporting it via the Yellow Card Scheme.

Body

A side effect of paroxetine can be not feeling as hungry as normal, which might lead to weight loss.

It is also possible to have a side effect of weight gain.

It is very difficult to know how it will affect each person who takes it.

Talk to your doctor about this if it worries you.

Sleep

You can feel sleepy in the first few days of taking paroxetine.

You can also have sleep problems (insomnia, vivid dreams).

These should, however, get better after the first week or two.

If you feel very sleepy, and you’ve been taking paroxetine for more than a month, you should go back to the doctor and see what else you can try.

Sex and fertility

Sex

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

• decreased libido (sex drive)
• difficulty getting an erection (getting hard) and ejaculating (coming)
• difficulty reaching orgasm (coming) the same way as before

More rarely, paroxetine can have the following side effects, which might affect your sex life:

• a painful erection that lasts for a long time (priapism). If this happens to you, visit a hospital or see your doctor immediately as this condition can be serious
• bleeding from the vagina, or irregular periods
• growth of the breasts and some milk flow, regardless of gender

These effects should pass after the first couple of weeks. If they do not, and this is a problem for you, go back to the doctor and see what else you could try.

The good effects of paroxetine may, after a while, have a positive impact on your sex life as your mood lifts and you become interested in life and relationships again.

Fertility

There have not been any reports of human fertility problems with paroxetine or other SSRI antidepressant medicines.

You should use good contraception when you are taking paroxetine. This is because there may be a slightly higher risk of heart problems in the developing baby if you take paroxetine in the early stages of pregnancy (see next section).

If you do become pregnant while you are on paroxetine, you should carry on taking the medicine and go back to your doctor as soon as possible to discuss whether you should stop or change your medicine.

Remember that you need to stay well through your pregnancy, and you may need a medicine to help you do that.

Pregnancy, post-natal and breastfeeding

Pregnancy

There may be a slightly higher risk of heart problems in the baby if you take paroxetine during the early stages of pregnancy.

If you and your doctor agree that you should carry on taking paroxetine during your pregnancy, you should tell your midwife that you are taking it at your first appointment.  

Post-natal

If paroxetine is taken in the last five months of a pregnancy, it can cause a serious condition called persistent pulmonary hypertension of the new-born (PPHN). This can make the baby breathe faster and look a bit blue in colour. PPHN affects around three in 1,000 babies born to mums who take SSRIs. This compares with a rate of two in 1,000 among babies born to mums who do not take SSRIs.

PPHN appears in the first 24 hours after birth. You will need help from the midwife and doctors, so it is better if they are looking out for symptoms.

Your newborn baby may also develop withdrawal effects, including:

• shaking
• being sick
• not feeding properly
• being very tired
• being unable to sleep
• crying a lot
• being too hot or too cold
• having extra muscle reactions (reflexes)
• extra alertness

These might not appear straight away, so you should look out for them over the first few days after the baby is born.

Breastfeeding

Paroxetine is passed to the baby in breastmilk in small amounts and this can help with any withdrawal effects.

Talk to your doctor or midwife about your feeding options.

Driving and transport

Do not drive or ride a bike just after you start taking paroxetine.

Taking paroxetine may affect your ability to do things like driving a car, riding a bike, using machines, or anything else that needs a lot of focus.

You might find it difficult to concentrate, you might feel sleepy and your eyesight may be blurred.

It might be best to stop doing these things for the first few days, until you know how paroxetine affects you or until the effects pass.

You could get a friend or family member to go with you and see if they notice a difference in your driving.

Do not worry - most people drive as normal while taking paroxetine.

School and exams

Try not to take paroxetine for the first time just before your exams.

You might find it difficult to concentrate, you might have sleep problems and your eyesight may be blurred. You also might find it difficult to sit still.

You should talk to your doctor about any future exams if you are starting paroxetine.

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 paroxetine to lift your mood and improve your motivation to study.

Do not worry - most people take exams as normal while taking paroxetine.

Friends and family

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

For guidance on this, check out our page on getting support with your medication.

Sport

Paroxetine is not a banned substance in sport.

Taking paroxetine may affect your ability to do things like riding a bike, competitive gymnastics, or anything else that needs a lot of focus.

You might find it difficult to concentrate, you might have sleep problems and your eyesight may be blurred. You may also find it difficult to sit still.

It might be best to stop such sports for the first few days, until you know how it affects you or the effects get better.

Do not worry - most people play sports as normal while taking paroxetine.

Alcohol and street drugs

Alcohol

You can continue to drink some alcohol while taking paroxetine.

Drinking alcohol every day, however, can make the symptoms of depression worse and you will not feel the benefit of your medicine.

The two together might make you sleepy or you might lose your focus when you first start taking paroxetine.

This could be dangerous if you drive or use machines or do anything that needs a lot of focus.

During the first few days, it might be best to stop drinking alcohol until you see how the medicine affects you, or until the effects pass.

Street drugs

We do not know how paroxetine mixes with street drugs, but it is likely to be similar to other SSRIs.

Cannabis can make drowsiness worse with paroxetine and give you a fast heartbeat.

Cannabis and other drugs may have their own side effects on your mental health, like anxiety or psychosis. For more information, have a look at our drugs and alcohol page.

Methadone can make drowsiness worse with paroxetine. The paroxetine is likely to increase the concentration of methadone in your body. There is also an increased risk of serotonin syndrome.

Paroxetine could raise the level of cocaine in your body, giving you a bigger reaction. There may be an increased chance of having a seizure (fit).

Taking paroxetine with cocaine, ecstasy or amfetamines 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.

Prescription medicines

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

Do not take paroxetine if you take an  antidepressant medicine called a monoamine oxidase inhibitor (MAOI), or if you have taken one in the last two weeks. MAOIs include moclobemide, isocarboxazid, phenelzine and tranylcypromine.

Talk to your doctor or pharmacist if you are taking any other medicines.

Tell the pharmacist you are taking paroxetine if you buy medicines over the counter (including things you put on your skin) for common illnesses.

References and further reading

For more helpful links and information, have a look at our references and further reading page.