Alka-seltzer original effervescent tablets contain three active ingredients, aspirin, sodium hydrogen carbonate and citric acid.
Aspirin belongs to a group of medicines called non-steroidal anti-inflammatory drugs (NSAIDs). It works by blocking the action of a substance in the body called cyclo-oxygenase.
Cyclo-oxygenase is involved in the production of various chemicals in the body, some of which are known as prostaglandins. Prostaglandins are produced in response to injury or certain diseases and would otherwise go on to cause pain, swelling and inflammation. Aspirin is therefore used to relieve pain and inflammation.
Sodium hydrogen carbonate and citric acid form antacids by their effervescent reaction with water. They decrease the acidity of the stomach's juices, by binding to and neutralising excess acid. This helps to relieve the symptoms of heartburn and indigestion and settles the stomach.
The combination of these medicines is used primarily to relieve headaches accompanied by an upset stomach, which can ofter occur after over-indulgence in food, drink or both. It can also be used to relieve various other types of aches and pains.
This medicine should not be used if you are allergic to any of its ingredients. Please inform your doctor or pharmacist if you have previously experienced such an allergy.
If you feel you have experienced an allergic reaction, stop using this medicine and inform your doctor or pharmacist immediately.
Certain medicines should not be used during pregnancy or breastfeeding. However, other medicines may be safely used in pregnancy or breastfeeding providing the benefits to the mother outweigh the risks to the unborn baby. Always inform your doctor if you are pregnant or planning a pregnancy, before using any medicine.
Medicines and their possible side effects can affect individual people in different ways. The following are some of the side effects that are known to be associated with this medicine. Just because a side effect is stated here, it does not mean that all people using this medicine will experience that or any side effect.
The side effects listed above may not include all of the side effects reported by the medicine's manufacturer.
For more information about any other possible risks associated with this medicine, please read the information provided with the medicine or consult your doctor or pharmacist.
Tell your doctor or pharmacist what medicines you are already taking, including those bought without a prescription and herbal medicines, before you start treatment with this medicine. Similarly, check with your doctor or pharmacist before taking any new medicines while taking this one, to ensure that the combination is safe.
People taking anticoagulant medicines used to prevent the blood clotting, eg warfarin, should not take aspirin to relieve pain or inflammation. This is because aspirin can irritate the stomach lining, as well as increase the effects of warfarin, both of which increase the likelihood of bleeding.
There may also be an increased risk of bleeding if aspirin is taken with the following medicines:
Aspirin reduces the rate at which the body can remove the medicine methotrexate. The two should not usually be used together, unless on the advice of a doctor.
There is an increased risk of side effects if aspirin is taken with other non-steroidal anti-inflammatory drugs (NSAIDs), eg ibuprofen, diclofenac, indometacin. For this reason, aspirin should not be taken with any other NSAID.
There may be an increased risk of bleeding or ulceration of the stomach or intestines if aspirin is taken with corticosteroids, eg prednisolone, dexamethasone.
There may be an increased risk of side effects if aspirin is taken with acetazolamide.
Antacids containing sodium, such as sodium hydrogen carbonate, can decrease the effectiveness of lithium and this medicine should therefore be avoided by people taking lithium.
There are currently no other medicines available in the UK that contain all three active ingredients aspirin, sodium hydrogen carbonate and citric acid.