Alka-Seltzer® XS
Aspirin, Paracetamol, Caffeine
Always take this medicine exactly as described in this leaflet or as your doctor or pharmacist has told you.
- Keep this leaflet. You may need to read it again.
- Ask your pharmacist if you need more information or advice.
- If you get any side effects, talk to your doctor or pharmacist. This includes any possible side effects not listed in this leaflet. See section 4.
- You must contact a doctor if you do not feel better or if you feel worse after 3 days.
1. What Alka-Seltzer XS is and what it is used for
2. What you need to know before you take Alka-Seltzer XS
3. How to take Alka-Seltzer XS
4. Possible side effects
5. How to store Alka-Seltzer XS
6. Contents of the pack and other information
Alka-Seltzer XS are effervescent tablets which dissolve in water to give a sparkling solution. The active substances are: aspirin (acetylsalicylic acid), paracetamol and caffeine.
Aspirin belongs to a group of medicines known as non-steroidal anti-inflammatory drugs (NSAIDS). Aspirin and paracetamol are both used for the treatment of pain and reduction of fever. Aspirin also has anti-inflammatory properties, whilst caffeine acts as mild stimulant.
Alka-Seltzer XS can be used for the:
- Treatment of mild to moderate pain including headache, migraine, backache (including lumbago), nerve pain (neuralgia and sciatica), period pain, toothache and sore throat.
- Symptomatic relief of colds and influenza.
- Relief of rheumatic pain (arthritis), muscle tenderness and stiffness (including fibrositis), muscular aches and pains.
- Effective reduction of high temperature.
- Are allergic (hypersensitive) to aspirin, any other salicylates (eg aloxiprin), paracetamol, caffeine or any of the ingredients (see Section 6).
- Have history of hypersensitivity reactions (eg asthma, rhinitis, urticaria) induced by pain relieving or anti-inflammatory medicines (eg NSAIDS or salicylates).
- Have uncontrolled high blood pressure.
- Have severe kidney or liver problems.
- Have severe heart problems (including severe blood vessel conditions).
- Have a disorder which causes excessive bleeding such as haemophilia.
- Have, or have had, a stomach or duodenal ulcer.
- Are on a high dose of methotrexate (15mg per week or more). If you are not sure, check with your doctor. Also see ‘Other medicines and Alka Seltzer XS’.
- Are in the last 3 months of your pregnancy.
- Are breastfeeding.
When taking aspirin (acetylsalicylic acid) serious allergic reactions which may include chest pain and even heart attack (Kounis syndrome) have been reported (see section 4). Stop taking Alka-Seltzer XS and seek medical care immediately when you notice chest pain with allergic reactions (such as skin rashes, shortness of breath).
Alka-Seltzer XS contains paracetamol. Do not take other products containing paracetamol whilst taking this product. The maximum dose of paracetamol for adults is 4g daily.
Talk to your doctor before taking Alka-Seltzer XS if you:
- Are allergic (hypersensitive) to any other pain relieving, anti-rheumatic or anti-inflammatory medicines (eg NSAIDS). For more information see section 4 ‘Possible Side Effects’.
- Suffer from tightness in the chest or asthma.
- Have low uric acid excretion, which is commonly associated with gout.
- Have a history of gastrointestinal disorders (regular stomach upsets).
- Have hyperthyroidism (an overactive thyroid)
- Have a deficiency in glucose-6-phosphate dehydrogenase (G6PD), since you may experience anaemia.
- Have kidney, liver, heart or blood circulation problems.
- Suffer from alcoholism or diabetes as Alka-Seltzer XS may increase the risk of liver damage.
- Are about to have surgery. Before the operation tell the doctor or surgeon that you are taking aspirin.
- Are in the first 6 months of pregnancy.
If you are not sure whether any of the above apply to you, speak to a doctor or pharmacist before taking Alka-Seltzer XS.
Aspirin can cause Reye’s syndrome when it is given to children. Reye’s syndrome is a very rare disease, which can be fatal. For this reason aspirin should not be given to children under 16 years, unless your doctor tells you to.
Please tell your doctor or pharmacist if you are taking or have recently taken any other medicines, including medicines obtained without a prescription.
Aspirin can affect the way in which some medicines work. These medicines include:
- Medication to prevent blood clotting (eg warfarin, heparin, ticlopidine).
- Medication to treat heart problems or to lower blood pressure (eg ACE inhibitors or digoxin).
- Medication to treat gout.
- Diuretics (to treat water retention).
- Medication to treat epilepsy (eg sodium valproate, phenytoin).
- Medication to lower blood sugar if you are diabetic.
- Methotrexate (to treat psoriasis, rheumatoid arthritis, Crohn’s disease and some types of cancer).
- Any pain-relieving or anti-inflammatory medicines.
- Some antidepressants known as SSRIs (eg fluoxetine, paroxetine).
- Medication to treat Addison’s disease (eg corticosteroids except hydrocortisone).
- Corticosteroids
Caffeine can affect the way in which some medicines work. These medicines include:
- Medicines used to treat seizures (such as phenobarbital, carbamazepine, valproate).
- Some antihistamines that can make you feel sleepy (first generation antihistamines, such as chlorpheniramine).
- Sympathomimetics, thyroxin (to increase heart rate).
- If you are allergic to xanthines (aminophylline, theophylline, etc.), you should not take Alka Seltzer XS, as you may also be allergic to caffeine.
- Oral contraceptives, cimetidine (used to treat heartburn), disulfiram, simultaneous use of some antibiotics can prolong the effects of caffeine.
Paracetamol can affect the way in which some medicines work. These medicines include:
- Metoclopramide (to treat nausea and vomiting).
- Domperidone (to treat nausea, vomiting, indigestion).
- Colestyramine (to treat high cholesterol).
- Propantheline (to treat excessive sweating, cramps or spasms of the stomach)
- Flucloxacillin (antibiotic), due to a serious risk of blood and fluid abnormality (high anion gap metabolic acidosis) that must have urgent treatment and which may occur particularly in case of severe renal impairment, sepsis (when bacteria and their toxins circulate in the blood leading to organ damage), malnutrition, chronic alcoholism, and if the maximum daily doses of paracetamol are used.
- Certain hypnotics and antiepileptics or rifampicin(concomitant use may lead to liver damage).
- Medication to prevent blood clotting (eg warfarin and other coumarins).
Avoid taking alcohol while taking Alka-Seltzer XS.
Do not take Alka-Seltzer XS if you are in the last 3 months of pregnancy as it could harm your unborn child or cause problems at delivery. Aspirin can cause kidney and heart problems in your unborn baby. It may affect your and your baby’s tendency to bleed and cause labour to be later or longer than expected. You should not take this product during the first 6 months of pregnancy unless absolutely necessary and advised by your doctor. Do not take Alka-Seltzer XS if you are breastfeeding. The product belongs to a group of medicines which may impair the fertility in women.
This effect is reversible on stopping the medicine. Speak to your doctor before taking this medicine if you are trying for a baby.
Always ask your doctor or pharmacist for advice before taking any medicine.
This medicine contains 472 mg sodium (main component of cooking/table salt) in each tablet. This is equivalent to 23.6% of the recommended maximum daily dietary intake of sodium for an adult.
Follow the directions below closely. You should ask your doctor or pharmacist if you are unsure how to use this medicine.
Alka-Seltzer XS tablets must always be dissolved in water before use.
Adults and children over 16:
Two tablets dissolved in half a glass (100ml) of water may be taken every 4 hours as required. You should not take more than 8 tablets in 24 hours.
Alka-Seltzer XS should not be taken by pregnant women unless directed by a doctor. If used during pregnancy, limit total caffeine intake (including other sources such as coffee) to 200 mg/day. Do not take more than 4 tablets (2 doses) in 24 hours.
Not recommended in children under 16.
Make sure you follow the dosage instructions and do not take more than the stated dose.
Do not take Alka-Seltzer XS for more than 3 days in a row. If you do not get better, talk to your doctor.
Talk to a doctor at once if you take too much of this medicine even if you feel well. This is because too much paracetamol can cause delayed, serious liver damage.
Like all medicines Alka-Seltzer XS can cause side effects although not everybody gets them.
If you experience any of the following side effects, stop taking Alka-Seltzer XS and go to your nearest Accident and Emergency Department or doctor immediately:
- An allergic reaction. Signs of allergic reaction may include: difficulty in breathing or swallowing, swelling of the face, lips, throat or tongue, skin rashes or itching, large or itchy wheals on the skin, attacks of sneezing, runny nose and itching eyes or water retention, heart racing.
- Skin reddening, blistering of lips, eyes or mouth, skin peeling.
- Mild stomach pain and heartburn. These are the most common side effects but can usually be avoided if aspirin is taken with food.
- Stomach ulcer or perforation, stomach bleeding, which may result in black or tarry stools, nausea, diarrhoea, vomiting.
- Dizziness or ringing in the ears.
- Increased bleeding/blood thinning (if you cut or injure yourself), including bruises, nose bleeds, bleeding gums.
- Internal bleeding which may result in anaemia causing weakness, increased tiredness and pale skin.
- An asthma attack if you are asthmatic and sensitive to aspirin, breathing difficulties (bronchospasm).
- Changes in normal liver activity in blood tests.
- Runny nose, blocked nose.
- Kidney problems.
- Liver problems.
- Heart-Related effects like racing heart, feeling warm or flushed, irregular heartbeats, high blood pressure, and a fast heartbeat.
- Headache, trouble falling/staying sleeping, and feeling restless.
- Frequency not known: Acute myocardial ischaemia (painful heart condition caused by lack of blood flow to the heart) with or without myocardial infarction (heart attack) occurring as part of an allergic reaction (Kounis syndrome).
Very rare cases of serious skin reactions have been reported.
If you have unusual stomach pains or react badly to this medicine in any other way, stop taking Alka-Seltzer XS and tell your doctor or pharmacist immediately.
If you get any side effects, talk to your doctor, pharmacist or nurse. This includes any possible side effects not listed in this leaflet. You can also report side effects directly via the Yellow Card Scheme at: www.mhra.gov.uk/yellowcard or search for MHRA Yellow Card in the Google Play or Apple App Store. By reporting side effects you can help provide more information on the safety of this medicine.
Keep out of the sight and reach of children.
Do not store above 25 °C. Store in a dry place. This product should be stored in its original carton.
This product is packaged in pouches containing 1 or 2 tablets. If the pouch is damaged or if a tablet is powdery or discoloured, do not use the tablet.
Do not use Alka-Seltzer XS after the expiry date which is stated on the carton and on the foil pouch. The expiry date refers to the last day of that month.
Do not throw away any medicines via wastewater or household waste. Ask your pharmacist how to throw away medicines you no longer use. These measures will help to protect the environment.
The active substances are aspirin (acetylsalicylic acid) (267mg per tablet), paracetamol (133mg per tablet) and caffeine (40mg per tablet).
The other ingredients are sodium hydrogen carbonate and citric acid.
See section 2 for sodium advice.
Alka-Seltzer XS comes in cartons containing 2, 10, 12, 20 or 30 white effervescent tablets packaged in foil pouches.
Not all pack sizes may be marketed.
Bayer plc
400 South Oak Way
Reading
RG2 6AD
UK
Bayer Bitterfeld GmbH
OT Greppin
Salegaster Chaussee 1
06803 Bitterfeld-Wolfen
Germany
This leaflet was last revised in June 2026.
Alka-Seltzer® is a registered trademark.
P0055018
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