Like all medicines, paroxetine can cause side effects in some people, but many people have no side effects or only minor ones.
Common side effects
These common side effects of paroxetine happen in more than 1 in 100 people. There are things you can do to help cope with them:
Feeling sick (nausea)
Try taking paroxetine with or after food. It may also help to stick to simple meals and avoid rich or spicy food.
Headaches
Make sure you rest and drink plenty of fluids. Try not to drink too much alcohol. Ask your pharmacist to recommend a painkiller.
Headaches should usually go away after the first week of taking paroxetine. Talk to your doctor if they last longer than a week or are severe.
Being unable to sleep
Try taking paroxetine first thing in the morning.
Diarrhoea
Drink plenty of water or other fluids to avoid dehydration. Signs of dehydration include peeing less than usual or having dark, strong-smelling pee. Do not take any other medicines to treat diarrhoea without speaking to a pharmacist or doctor.
If you're taking the combined contraceptive pill or progestogen-only pill and you have severe diarrhoea for more than 24 hours, your contraception may not protect you from pregnancy. Check the pill packet for advice.
Feeling tired or weak
If paroxetine makes you feel tired or weak, stop what you're doing and sit or lie down until you feel better. Do not drive or use tools or machinery if you're feeling tired. It's best not drink alcohol as it will make you feel worse.
If these symptoms do not go away after a week or two, ask your doctor for advice.
Serious side effects
Serious side effects are rare and happen in less than 1 in 1,000 people.
Book an appointment with your doctor if you:
- lose or gain weight without trying
- have changes in your periods such as heavy bleeding, spotting or bleeding between periods
Call your doctor or call 111 straight away if you:
- get constant headaches, long lasting confusion or weakness, or frequent muscle cramps – these can all be signs of low sodium levels in your blood
- cough up blood or have blood in your pee
- have black or red poo or blood in your vomit – these can be signs of bleeding from the gut
- are bleeding from the gums or have bruises that appear without a reason or that get bigger
- are feeling restless or cannot sit or stand still
- get blurred vision
Immediate action required: Call 999 or go to A&E now if:
- you have chest pain or pressure or shortness of breath – chest pain is a possible symptom of a heart attack and needs to be checked out as soon as possible
- you get painful erections that last longer than 2 hours – this may happen even when you're not having sex
- you have thoughts about harming yourself or ending your life
- you have any heavy bleeding or bleeding that you cannot stop such as cuts or nosebleeds that do not stop within 10 minutes
Serious allergic reaction
In rare cases, it's possible to have a serious allergic reaction (anaphylaxis) to paroxetine.
Immediate action required: Call 999 now if:
- your lips, mouth, throat or tongue suddenly become swollen
- you're breathing very fast or struggling to breathe (you may become very wheezy or feel like you're choking or gasping for air)
- your throat feels tight or you're struggling to swallow
- your skin, tongue or lips turn blue, grey or pale (if you have black or brown skin, this may be easier to see on the palms of your hands or soles of your feet)
- you suddenly become very confused, drowsy or dizzy
- someone faints and cannot be woken up
- a child is limp, floppy or not responding like they normally do (their head may fall to the side, backwards or forwards, or they may find it difficult to lift their head or focus on your face)
You or the person who's unwell may also have a rash that's swollen, raised, itchy, blistered or peeling.
These can be signs of a serious allergic reaction and may need immediate treatment in hospital.
Long-term side effects
For most people, paroxetine is safe to take for a long time.
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.
Taking paroxetine for more than a year has also been linked to a small, increased risk of getting diabetes. But you will be regularly checked for this.
Other side effects
These are not all the side effects of paroxetine. For a full list, see the leaflet inside your medicine packet.
You can report any suspected side effect using the Yellow Card safety scheme.