Aspirin is an everyday painkiller for aches and pains such as headache, toothache and period pain. It can also be used to treat colds and "flu-like" symptoms, and to bring down a fever (38C and above). It is also known as acetylsalicylic acid.

Aspirin is also available combined with other ingredients in some cold and flu remedies.

You can buy most types of aspirin from pharmacies, shops and supermarkets. Some types are only available on prescription.

It comes as tablets or suppositories - medicine that you push gently into your anus. It also comes as a gel for mouth ulcers and cold sores.

If you've had a stroke or heart attack or are at high risk of a heart attack, your doctor may recommend that you take a daily low-dose aspirin. This is different to taking aspirin for pain relief. Only take low-dose aspirin if your doctor recommends it. Read our information on low-dose aspirin.

• It's best to take aspirin with food. That way, you'll be less likely to get an upset stomach or stomach ache.
• Never give aspirin to children under the age of 16 (unless their doctor prescribes it). It can make children more likely to develop a very rare but serious illness called Reye's syndrome.
• Aspirin is generally safe to take as a painkiller in the first 6 months of pregnancy (up to 30 weeks). It's not recommended after 30 weeks of pregnancy or while breastfeeding.
• Many supermarkets, shops and pharmacies sell their own brand aspirin. Aspirin is also called by the brand names Caprin, Disprin, and Nu-Seals. The brand name for aspirin as a suppository is Resprin. Aspirin is an ingredient in Anadin Original, Anadin Extra, Alka-Seltzer Original, Alka-Seltzer XS and Beechams Powders.
• Aspirin as a mouth gel has the brand name Bonjela. Like other aspirin products, it's only for people aged 16 and over. Bonjela Teething Gel and Bonjela Junior Gel do not contain aspirin, so you can give them to children under 16.

Most people aged 16 and over can safely take aspirin.

However, aspirin is not suitable for some people.

Never give aspirin to a child younger than 16, unless their doctor prescribes it. There's a possible link between aspirin and Reye's syndrome in children. Reye's syndrome is a very rare illness that can cause serious liver and brain damage.

To make sure aspirin as a painkiller (including mouth gel) is safe for you, tell your doctor or pharmacist if you have:

• an allergy to aspirin or similar painkillers such as ibuprofen
• ever had a stomach ulcer
• recently had a stroke (although depending on the kind of stroke you've had, your doctor may recommend that you take low-dose aspirin to prevent another one)
• high blood pressure (hypertension)
• indigestion
• asthma or lung disease
• ever had a blood clotting problem
• liver or kidney problems
• gout - it can get worse for some people who take aspirin
• heavy periods - they can get heavier with aspirin

If you're pregnant, trying to get pregnant or if you want to breastfeed, check with your doctor that it's safe for you to take aspirin.

The dose of aspirin that's right for you depends on the kind of aspirin you're taking, why you're taking it and how well it helps your symptoms.

Aspirin tablets

Aspirin usually comes as 300mg tablets.

The usual dose is 1 or 2 tablets every 4 to 6 hours.

Aspirin comes as several different types of tablet:

• standard tablets - that you swallow whole with water
• soluble tablets - that you dissolve in a glass of water
• enteric coated tablets - that you swallow whole with water

Enteric tablets have a special coating that may make them gentler on your stomach. Do not chew or crush them because it will stop the coating working. If you also take indigestion remedies, take them at least 2 hours before or after you take your aspirin. The antacid in the indigestion remedy affects the way the coating on these tablets works.

You can buy aspirin tablets and soluble tablets from both pharmacies and supermarkets.

Aspirin suppositories

Aspirin suppositories are medicine that you push gently into your bottom. To use them, follow the instructions on the leaflet inside the packet.

Aspirin suppositories come in 2 strengths. They contain 150mg or 300mg of aspirin. You can buy them from a pharmacy.

If you're taking 150mg: the usual dose is 3 to 6 suppositories. This is 450mg to 900mg every 4 hours. The maximum dose is 24 of the 150mg suppositories in 24 hours.

If you're taking 300mg: the usual dose is 1 to 3 suppositories. This is 300mg to 900mg every 4 hours. The maximum dose is 12 of the 300mg suppositories in 24 hours.

If you need a dose of 450mg or 750mg, your doctor or pharmacist will give you a mixture of strengths and explain how to take it.

Aspirin mouth gel

You can buy aspirin mouth gel (Bonjela) from pharmacies and supermarkets. Do not give Bonjela to children. You can give Bonjela Teething Gel or Bonjela Junior to children as they do not contain aspirin.

For mouth ulcers or sores, massage about a centimetre (half an inch) of gel onto the sore area. Apply it to the inside of your mouth or gums every 3 hours as needed.

If you have dentures (false teeth), take them out before you apply the mouth gel. Then wait at least 30 minutes after applying the gel before putting your dentures back in your mouth.

What if I take too much?

Taking 1 or 2 extra tablets by accident is unlikely to be harmful.

The amount of aspirin that can lead to overdose varies from person to person.

It's safe to take aspirin with paracetamol or codeine.

But do not take aspirin with ibuprofen or naproxen without talking to a doctor. Aspirin, ibuprofen and naproxen belong to the same group of medicines called non-steroidal anti-inflammatory drugs (NSAIDs). If you take them together, aspirin plus ibuprofen or naproxen may increase the chance of you getting side effects like stomach ache.

Speak to a pharmacist if you're unsure about dosages and timings when taking aspirin with other painkillers.

Like all medicines, aspirin can cause side effects although not everyone gets them.

Common side effects

Common side effects of aspirin happen in more than 1 in 100 people. Talk to your doctor or pharmacist if the side effects bother you or do not go away:

• mild indigestion
• bleeding more easily than normal - because aspirin thins your blood it can sometimes make you bleed more easily. For example, you may get nosebleeds, bruise more easily, and if you cut yourself, the bleeding may take longer than normal to stop.

Serious side effects

It happens rarely, but some people have serious side effects after taking aspirin.

Call a doctor straight away if you get:

• red, blistered and peeling skin
• coughing up blood or blood in your pee, poo or vomit
• yellow skin or the whites of your eyes turn yellow - this can be a sign of liver problems
• painful joints in the hands and feet - this can be a sign of high levels of uric acid in the blood
• swollen hands or feet - this can be a sign of water retention

Serious allergic reaction

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

These are not all the side effects of aspirin. For a full list see the leaflet inside your medicines packet.

What to do about:

• mild indigestion - take your aspirin with food. If the indigestion still does not go away, it could be a sign that the aspirin has caused a stomach ulcer. Talk to your doctor - they may prescribe something to protect your stomach or switch you to a different medicine.
• bleeding more easily than normal - be careful when doing activities that might cause an injury or a cut. It might be best to stop doing contact sports such as football, rugby and hockey, while you're taking aspirin. Wear gloves when you use sharp objects like scissors, knives, and gardening tools. Use an electric razor instead of wet shaving and use a soft toothbrush and waxed dental floss to clean your teeth. See a doctor if you're worried about any bleeding.

It's safe to take aspirin as a painkiller in the first 6 months of pregnancy (up to 30 weeks).

Do not take aspirin for pain relief after 30 weeks of pregnancy. It can cause complications - including breathing and blood clotting problems - in the newborn baby. For most women, paracetamol is the best painkiller to take in late pregnancy.

If you've taken aspirin after week 30 of pregnancy, especially if you've taken it for a long time, tell your doctor or midwife straight away so they can check the health of your baby.

For more information about how aspirin can affect you and your baby during pregnancy, visit the Best Use of Medicines in Pregnancy (BUMPS) website.

Breastfeeding and aspirin

Aspirin is not normally recommended during breastfeeding. For most women, it's better to take paracetamol or ibuprofen to control pain or fever while you're breastfeeding.

Some medicines interfere with the way aspirin works.

Tell your doctor if you're taking these medicines before you start taking aspirin:

• medicines to thin blood or prevent blood clots such as clopidogrel and warfarin - taking them with aspirin might cause bleeding problems
• medicines for pain and inflammation such as ibuprofen and prednisolone
• medicines to prevent organ rejection after transplant such as ciclosporin and tacrolimus
• medicines to treat high blood pressure such as furosemide and ramipril
• digoxin, a medicine for heart problems
• lithium, a medicine for mental health problems
• acetazolamide, for an eye problem called glaucoma
• methotrexate, a medicine used to stop the immune system overreacting and sometimes to treat some types of cancer
• diabetes medicines, such as insulin and gliclazide

Mixing aspirin with herbal remedies or supplements

Aspirin may not mix well with quite a lot of complementary and herbal medicines. Aspirin could change the way they work and increase your chances of side effects.

For safety, speak to your pharmacist or doctor before taking any herbal or alternative remedies with aspirin.