Oxybutynin is a medicine used to treat symptoms of an overactive bladder. These can include:

• a sudden and urgent need to pee (urinary urgency)
• needing to pee more often than usual (urinary frequency)
• wetting yourself if you cannot make it to the loo in time (urinary incontinence)

It's also used to treat bedwetting in children (nocturnal enuresis).

Oxybutynin works by relaxing the muscles around your bladder. This means your bladder can hold more liquid and you do not need to pee as often or as urgently.

Oxybutynin is only available on prescription.

It comes as standard tablets for immediate release, or slow-release tablets (also called prolonged release), a liquid to swallow, or as patches.

• Oxybutynin may take up to 4 weeks to reach its full effect. If the symptoms do not improve after 1 to 2 weeks, talk to your doctor.
• Your doctor will do a review after 4 weeks to check oxybutynin is still working and is the best treatment for you.
• Your doctor will also check that your treatment is still needed every 6 to 12 months .
• Common side effects of oxybutynin include dry mouth, blurred vision, constipation and feeling dizzy or sleepy.
• It's best not to drink alcohol when you first start taking oxybutynin, as it can make you very sleepy.

Oxybutynin can be taken by adults and children aged 5 years or over.

Oxybutynin is not suitable for some people. To make sure it's safe for you, tell your doctor before starting oxybutynin if you have:

• ever had an allergic reaction to oxybutynin, any of its ingredients or any other medicine
• myasthenia gravis, a rare long-term condition that causes muscle weakness
• an eye problem called glaucoma
• difficulty peeing, or an enlarged prostate
• ulcerative colitis or Crohn's disease
• heart problems, including a very fast heart rate or high blood pressure
• thyroid, kidney or liver problems

Always read the information that comes with your medicine.

Dosage and strength of standard tablets

Standard tablets come as either 2.5mg, 3mg or 5mg.

The usual starting dose of 2.5mg is 1 tablet, taken twice a day, in the morning or evening, or 1 tablet, taken 3 times a day.

If you take 3 doses a day, space each dose evenly throughout the day. You could take it first thing in the morning, in the middle of the afternoon and at bedtime.

Dosage and strength of slow-release tablets

Slow-release tablets come in 2 strengths, 5mg and 10mg. The usual starting dose is 5mg once a day.

Dosage and strength of liquid

Oxybutynin is available as a liquid for children and people who find it difficult to swallow tablets. It comes in 2 strengths:

• 2.5mg of oxybutynin in a 5ml spoonful
• 5mg in oxybutynin in a 5ml spoonful

The usual starting dose for an adult is 5mg, taken twice a day (12 hours apart), or 5mg, taken 3 times a day.

The dose will usually be lower for adults over 65 and children.

If you take 3 doses a day, space each dose evenly throughout the day. You could take it first thing in the morning, in the middle of the afternoon and at bedtime.

How to take standard tablets

Swallow the tablets whole with a drink of water. You can take tablets with or without food.

How to take slow-release tablets

Slow-release tablets release oxybutynin slowly and evenly throughout the day.

Swallow these tablets whole with a drink of water. Do not break, crush or chew them.

Try to take your tablet at the same time each day. This will help you to remember to take them.

Part of the tablet can pass through your body and you might see it in your poo. Do not worry, this is normal and does not affect the way the medicine works.

How to take liquid

If you are giving this medicine to a child to help stop them wetting the bed, give the last dose just before bedtime.

Oxybutynin liquid will come with a plastic syringe or spoon to help you measure out the right dose. If you do not have one, ask your pharmacist for one. Do not use a kitchen teaspoon as it will not give the right amount of medicine.

How to use patches

Oxybutynin patches are applied twice a week.

They work like a plaster., you stick them to your skin.

1. Follow the instructions that come with the patches.
2. Stick a patch to clean, dry skin on your stomach, hip or bottom twice a week (every 3 or 4 days).
3. Change the patch on the same 2 days every week, such as every Sunday and Wednesday, or Monday and Thursday.
4. Remove the old patch before sticking on the new one.
5. Stick the new patch to a different area of your stomach, hips or bottom. Using the same area may irritate your skin. Do not stick the patch in the same place for at least 1 week.

Will my dose go up or down?

Your doctor may increase your dose depending on how the medicine works for you.

What if I forget to take it?

If you forget to take a dose, take it as soon as you remember, unless it's almost time for your next dose. In this case, just skip the missed dose and take your next dose at the usual time.

Never take 2 doses at the same time. Never take an extra dose to make up for a forgotten one.

If you often forget doses, it may help to set an alarm to remind you. You could also ask your pharmacist for advice on other ways to remember to take your medicine.

What if I take too much?

Taking 1 extra dose of oxybutynin is unlikely to harm you.

However, you may get more side effects, such as a dry mouth or headache.

The amount of oxybutynin that can lead to an overdose varies from person to person, and too much oxybutynin can be dangerous.

Like all medicines, oxybutynin can cause side effects, but not everyone gets them.

Keep taking oxybutynin, but talk to your doctor or pharmacist if these side effects bother you or do not go away, or if you notice any other possible side effects.

Common side effects of oxybutynin

These common side effects of oxybutynin may affect more than 1 in 100 people:

• dry mouth
• headache
• feeling dizzy, sleepy, or a spinning sensation (vertigo)
• diarrhoea or being sick (vomiting)
• constipation
• farting and burping (wind)
• stomach pain
• dry eyes
• blurred vision
• problems or pain when peeing, and not being able to empty your bladder

Serious side effects

Serious side effects are rare.

Tell your doctor if you have:

• stomach pain (especially after meals), feeling sick or being sick, a persistent urge to poo, not being able to poo or you have runny poos – these are all signs of faecal impaction, where large, hardened poo gets stuck and you cannot push it out
• difficulty fully emptying your bladder, or difficulty in starting to pee – these are signs of urinary retention, where pee builds up in your bladder because you're unable to pee
• high temperature or chills, burning sensation when peeing, pain in your back or side, or bloody or cloudy pee – these can be signs of a severe urinary tract infection (UTI)
• swollen ankles or legs (oedema) – where fluid builds up in your legs

Do not take any more oxybutynin and call a doctor straight away if you feel you're overheating and not sweating when you're in hot surroundings.

Serious allergic reaction

In rare cases, it's possible to have a serious allergic reaction (anaphylaxis) to oxybutynin.

What to do about:

• dry mouth – try sugar-free gum or having sugar-free sweets. Having a dry mouth can cause tooth decay or a fungal infection. It also might stop medicine that you put under your tongue from dissolving properly, such as medicine for angina.
• headaches – make sure you rest and drink plenty of fluids. Avoid alcohol. Ask your pharmacist to recommend a painkiller. Talk to your doctor if your headache is severe or lasts longer than 1 or 2 days.
• feeling dizzy, sleepy or a spinning sensation – do not drive, cycle, use tools, or operate machinery. Avoid drinking alcohol, as this may make your symptoms worse. Talk to your doctor if the dizziness or sleepiness bothers you or lasts more than a few days.
• diarrhoea or being sick – drink lots of fluids, such as water or squash, to avoid dehydration. Take small, frequent sips if you're being sick. Signs of dehydration include peeing less than usual or having dark, strong-smelling pee. Do not take any other medicines without speaking to a pharmacist or doctor, if the effects last more than 1 or 2 days.
• constipation – eat more high-fibre foods, such as fresh fruit and vegetables and cereals, and drink plenty of water. Try to exercise more regularly, for example, by going for a daily walk or run. If this does not help, talk to a pharmacist or doctor. Watch this short video about how to treat constipation.
• farting and burping – eat less foods that cause wind, like lentils, peas, beans and onions. It might also help to eat smaller and more frequent meals, eat and drink slowly, and exercise regularly. Ask your pharmacist about remedies you can buy to help with trapped wind.
• stomach pain – try to rest and relax. It can help to eat and drink slowly and have smaller and more frequent meals. Try putting a heat pad or a covered hot water bottle on your stomach to help. If you have episodes of severe, griping pain, speak to your pharmacist or doctor.
• dry eyes – ask your pharmacist or optician to recommend some eye drops. If you wear contact lenses and these become uncomfortable, you might have to wear glasses instead while you're taking this medicine.
• blurred vision – do not drive or cycle until you can see clearly again. Do not take your next dose of oxybutynin if your vision is still blurred. Speak to your doctor or pharmacist if your vision has not returned to normal a day after taking your last dose.
• problems or pain when peeing – try to relax when you pee. Do not try to force the flow of urine. If it does not happen, try again later. Talk to a doctor urgently if you cannot pee at all.

Oxybutynin is occasionally used in pregnancy when bladder symptoms are severe and cannot be controlled any other way.

If you're pregnant or trying to get pregnant, talk to your doctor about whether taking oxybutynin is right for you.

Oxybutynin and breastfeeding

Oxybutynin is not usually recommended while breastfeeding. However, you may still need to take it.

It's not known how much oxybutynin gets into breast milk, but it's likely to be small.

If your doctor says it's OK for you to keep taking oxybutynin, monitor your baby for possible side effects, such as constipation, peeing less and colic.

Talk to your doctor, midwife, or health visitor if you have any concerns about your baby, or you do not think your baby is putting on enough weight.

For more information about treating bladder problems (urinary incontinence) during pregnancy, read this leaflet on the Best Use of Medicines in Pregnancy (BUMPs) website.

Oxybutynin may affect the way other medicines work, and other medicines may affect how oxybutynin works.

Tell your pharmacist or doctor if you're taking:

• amantadine, a medicine used for Parkinson's disease or for infections
• levodopa, used to treat Parkinson's disease
• phenothiazines, clozapine, haloperidol or benperidol, medicines for mental health problems
• donepezil, rivastigmine, galantamine or tacrine, medicines used for dementia
• amitriptyline, imipramine or dosulepin (tricyclic antidepressants), medicines for depression
• medicines used to make you feel sleepy (sedatives)
• anti-sickness medicines like prochlorperazine
• medicines for stomach and bowel-related problems like domperidone and metoclopramide
• digoxin, quinidine or disopyramide, medicines used to treat heart problems
• dipyridamole, used to treat blood problems
• chlorphenamine or diphenhydramine, medicines used to treat allergies
• any medicines used to treat irritable bowel syndrome, asthma, incontinence, motion sickness or movement disorders related to Parkinson's disease, that work in a similar way to oxybutynin

Mixing oxybutynin with herbal remedies and supplements

There's very little information about taking oxybutynin with herbal remedies and supplements. These remedies are not tested in the same way as medicines.

Some herbal medicines can make you feel sleepy, cause a dry mouth, or make it difficult to pee. Their effect is similar to oxybutynin. This can increase your risk of getting side effects or make your side effects worse.