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Pack Alka-Seltzer Original 8 Effervescent Tablets - 16 Tablets In Total

Pack Alka-Seltzer Original 8 Effervescent Tablets - 16 Tablets In Total

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  • ✔️ Relieves headache and indigestion simultaneously with one dose
  • ✔️ Effervescent format dissolves fast for rapid symptom relief
  • ✔️ Contains aspirin 324mg to target mild-to-moderate pain effectively
  • ✔️ Sodium bicarbonate neutralises excess stomach acid quickly
  • ✔️ Twin-pack of 16 tablets — practical supply for home use

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What Are Alka-Seltzer Original Tablets and How Do They Help?

 

Alka-Seltzer Original tablets are a well-known over-the-counter remedy that combines three active ingredients — aspirin, sodium bicarbonate, and citric acid — to tackle headache, mild-to-moderate pain, and indigestion at the same time. Each pack in this twin-pack bundle contains 8 effervescent tablets, giving you 16 tablets in total for £6.99. That makes it a practical option to keep in your medicine cabinet at home or to pop in your bag when you're travelling. If you regularly deal with the uncomfortable combination of a headache alongside an upset stomach, this product is designed with exactly that in mind. You can explore our wider pain relief collection if you're looking for additional options alongside this product.

Alka-Seltzer has been used in the UK for decades, and its effervescent format means the active ingredients are already dissolved when you drink them — which may help them act more quickly than a standard solid tablet. The NHS notes that aspirin is an established analgesic and anti-inflammatory agent used for mild-to-moderate pain relief.

 

How Do Alka-Seltzer Original Tablets Work?

 

The three ingredients each play a distinct role:

  • Aspirin (324mg per tablet): A non-steroidal anti-inflammatory drug (NSAID) that works by inhibiting cyclooxygenase (COX) enzymes, reducing the production of prostaglandins — the chemicals responsible for pain, inflammation, and fever.
  • Sodium bicarbonate (1625mg per tablet): An antacid that neutralises excess stomach acid, helping to relieve heartburn, acid indigestion, and the stomach discomfort that can accompany a headache or hangover.
  • Citric acid (965mg per tablet): Reacts with the sodium bicarbonate to produce the characteristic fizzing action, aiding dissolution and making the solution easier to drink.

Together, these ingredients address both the pain and the digestive discomfort that often occur together — for example, after a heavy meal or a night out.

 

Who Is Alka-Seltzer Original Suitable For?

 

This product is suitable for adults and young people aged 16 and over who need short-term relief from mild-to-moderate pain combined with indigestion or upset stomach. It is particularly useful for:

  • Adults with a headache accompanied by stomach discomfort
  • People experiencing indigestion or heartburn after eating
  • Adults seeking relief from the symptoms of a hangover (headache, nausea, stomach upset)
  • Those who prefer a liquid-format medicine over swallowing solid tablets

It is not suitable for children under 16, people with a known allergy to aspirin or other NSAIDs, those with active peptic ulcers, or individuals with haemophilia or other bleeding disorders. If you have any doubt about suitability, speak to your pharmacist before use.

 

How Does Alka-Seltzer Original Compare to Other Pain Relief Options?

 

Feature Alka-Seltzer Original Standard Paracetamol Tablets
Active ingredient Aspirin + sodium bicarbonate + citric acid Paracetamol 500mg
Treats indigestion Yes — antacid component included No
Suitable for under 16s No Yes (age-appropriate doses)
Format Effervescent (dissolved in water) Solid tablet, swallowed whole

 

How Should You Store Alka-Seltzer Original Tablets?

 

Store your Alka-Seltzer Original tablets below 25°C in a dry place, away from direct sunlight and moisture. The effervescent tablets are particularly sensitive to humidity — even brief exposure to damp air can cause them to begin reacting prematurely, reducing their effectiveness. Always reseal the tube tightly after use and keep the product out of reach and sight of children. Do not use after the expiry date printed on the packaging. If you're also managing digestive health concerns, our indigestion collection has a range of complementary products worth exploring.

This product is a medicine. Speak to your doctor or pharmacist before using if you have an underlying medical condition or are taking other medicines.

Alka-Seltzer Original 16 Effervescent Tablets specifications
Treatment category Pain relief / Antacid
Mechanism of action COX enzyme inhibition (aspirin); acid neutralisation (sodium bicarbonate)
Effective for Headache, mild-to-moderate pain, indigestion, heartburn, upset stomach
Suitable for Adults and young people aged 16 and over
Active ingredients Aspirin 324mg, Sodium Bicarbonate 1625mg, Citric Acid 965mg (per tablet)
Pack size 16 tablets (2 × 8-tablet packs)
UK classification General Sale List (GSL)
Drug class NSAID / Antacid combination
Preparation Effervescent tablet
Route of administration Oral (dissolved in water)

Specifications of Alka-Seltzer Original 16 Effervescent Tablets

 

What Is Alka-Seltzer Original and What Is It Used For?

 

Alka-Seltzer Original effervescent tablets are an over-the-counter (OTC) medicine used for the short-term relief of mild-to-moderate pain — including headache, migraine headache, toothache, and period pain — as well as indigestion, heartburn, and upset stomach. Each tablet contains aspirin 324mg, sodium bicarbonate 1625mg, and citric acid 965mg. The tablets are dissolved in water before drinking, which means you're taking a liquid solution rather than swallowing a solid tablet. This format is particularly helpful if you struggle to swallow tablets or want a faster-acting option. Alka-Seltzer Original tablets are classified as a General Sale List (GSL) medicine in the UK, meaning they can be purchased without a prescription.

 

What Do You Need to Know Before Using Alka-Seltzer Original?

 

Before taking this medicine, it's important to check whether it's right for you. Do not take Alka-Seltzer Original if any of the following apply:

  • You are allergic to aspirin, salicylates, or any other NSAID (e.g. ibuprofen)
  • You are under 16 years of age (risk of Reye's syndrome)
  • You have or have had a peptic ulcer or gastrointestinal bleeding
  • You have haemophilia or another bleeding disorder
  • You have severe kidney, liver, or heart failure
  • You are in the third trimester of pregnancy
  • You are taking anticoagulants such as warfarin

Talk to your pharmacist or GP before taking this product if you have asthma, gout, or are breastfeeding. The sodium content is also worth noting — each tablet contains approximately 445mg of sodium, which is relevant if you are on a low-sodium diet.

Known drug interactions include:

  • Anticoagulants (e.g. warfarin, heparin) — increased bleeding risk
  • Other NSAIDs or aspirin-containing products — increased side effect risk
  • Methotrexate — aspirin can increase methotrexate toxicity
  • SSRIs (e.g. fluoxetine) — increased risk of gastrointestinal bleeding
  • Antidiabetic medicines — aspirin may enhance the glucose-lowering effect
  • Corticosteroids — increased risk of gastrointestinal ulceration

 

How Should You Use Alka-Seltzer Original Tablets?

 

Always use this medicine exactly as described on the label or as directed by your pharmacist. The tablets must be fully dissolved in water before drinking — never swallow them whole or chew them.

  1. Fill a glass with at least 200ml (roughly a full tumbler) of water.
  2. Drop 2 tablets into the water.
  3. Wait until the tablets have completely dissolved and the fizzing has stopped.
  4. Drink the solution immediately.
  5. Wait at least 4 hours before taking another dose.
  6. Do not exceed 6 tablets (3 doses) in any 24-hour period.
Indication Age Group Dose Frequency
Headache / mild pain Adults & young people 16+ 2 tablets dissolved in water Up to 3 times daily (every 4 hours)
Indigestion / heartburn Adults & young people 16+ 2 tablets dissolved in water Up to 3 times daily (every 4 hours)
Under 16 years Children Not suitable — do not use

If your symptoms persist for more than 3 days, or worsen at any point, stop taking the tablets and consult your GP or pharmacist. You might also find our cold and flu collection useful if your headache is associated with cold or flu symptoms.

 

What Are the Possible Side Effects of Alka-Seltzer Original?

 

Like all medicines, Alka-Seltzer Original can cause side effects, although not everyone experiences them. The NHS advises that aspirin-based products can irritate the stomach lining, particularly when taken on an empty stomach.

Common side effects:

  • Nausea or stomach discomfort
  • Indigestion or heartburn (paradoxically, in some individuals)
  • Mild stomach pain

Less common side effects:

  • Gastrointestinal bleeding (black or tarry stools, vomiting blood)
  • Allergic reactions — rash, itching, swelling, or difficulty breathing
  • Worsening of asthma symptoms (aspirin-sensitive asthma)
  • Tinnitus (ringing in the ears) — a sign of aspirin toxicity at higher doses

Stop taking the tablets immediately and seek urgent medical attention if you experience signs of a serious allergic reaction, gastrointestinal bleeding, or difficulty breathing.

 

How Should You Store Alka-Seltzer Original Tablets?

 

  • Store below 25°C in a dry place — humidity will degrade effervescent tablets rapidly
  • Keep away from direct sunlight and heat sources
  • Always replace the cap firmly after removing tablets
  • Keep out of the sight and reach of children
  • Do not use after the expiry date printed on the tube
  • Do not store in a bathroom cabinet — steam and moisture can affect the tablets

If you're managing multiple health concerns alongside pain relief, our vitamins and supplements collection includes products that support general wellbeing.

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Your safety and success are our highest priorities. Our medical team rigorously evaluates every product and piece of advice we provide, ensuring you receive only the most effective, science-backed solutions available.

Frequently Asked Questions

Where can I buy Alka-Seltzer Original tablets online in the UK?

You can buy Alka-Seltzer Original tablets online from Cured Pharmacy, a GPhC-registered UK online pharmacy. This twin-pack of 16 effervescent tablets is available for £6.99 with fast UK delivery. Browse our full pain relief collection for more options alongside this product.

How do Alka-Seltzer Original tablets work in the body?

Alka-Seltzer Original tablets contain aspirin, which inhibits COX enzymes to reduce prostaglandin production — the chemicals that cause pain and inflammation. Sodium bicarbonate neutralises excess stomach acid, addressing indigestion at the same time. The citric acid creates the fizzing reaction that helps the ingredients dissolve quickly and evenly in water.

How do I use Alka-Seltzer Original tablets step by step?

Drop 2 tablets into a glass containing at least 200ml of water and wait for them to fully dissolve before drinking. Never swallow the tablets whole or chew them — they must be taken as a dissolved solution. Drink the solution as soon as it has finished fizzing for best results.

What is the correct dose of Alka-Seltzer Original for adults?

The standard adult dose is 2 tablets dissolved in water, taken up to 3 times daily with at least 4 hours between each dose. Do not exceed 6 tablets (3 doses) in any 24-hour period. If you are elderly or have kidney or liver concerns, speak to your pharmacist before use as a lower dose may be more appropriate.

What is the best time to take Alka-Seltzer Original tablets?

Take Alka-Seltzer Original as soon as your symptoms begin — it is designed for on-demand, short-term relief rather than regular scheduled dosing. Taking it with or after food may help reduce the risk of stomach irritation, particularly if you are prone to digestive sensitivity. Avoid taking it on a completely empty stomach where possible.

What are the side effects of Alka-Seltzer Original tablets?

Common side effects include nausea, stomach discomfort, and mild indigestion. Less commonly, aspirin can cause gastrointestinal bleeding — signs include black or tarry stools or vomiting blood — and in aspirin-sensitive individuals, it may worsen asthma symptoms. Stop use immediately and seek medical advice if you experience any serious or unexpected symptoms.

How do I manage side effects of Alka-Seltzer Original?

Taking the dissolved solution with food or a glass of milk can help reduce stomach irritation. If you experience persistent nausea or stomach pain, stop taking the tablets and speak to your pharmacist. For mild digestive discomfort, our indigestion collection includes products that may help settle your stomach.

Who should not take Alka-Seltzer Original tablets?

Alka-Seltzer Original is not suitable for children under 16 (due to the risk of Reye's syndrome), people with a known allergy to aspirin or NSAIDs, those with active peptic ulcers, or individuals taking anticoagulants such as warfarin. It is also not recommended during the third trimester of pregnancy. Always read the full label before use.

Can I take Alka-Seltzer Original tablets during pregnancy?

Aspirin-containing products are generally not recommended during pregnancy, particularly in the third trimester, as they may affect the baby's circulation and delay labour. If you are pregnant or breastfeeding, speak to your GP or midwife before taking this product. There are paracetamol-based alternatives that are considered safer during pregnancy.

Can I take Alka-Seltzer Original if I have asthma?

Some people with asthma are sensitive to aspirin and NSAIDs, and taking them can trigger or worsen asthma symptoms — this is known as aspirin-exacerbated respiratory disease (AERD). If you have asthma, speak to your GP or pharmacist before taking Alka-Seltzer Original. They can advise on whether it is safe for you or suggest a more suitable alternative.

Does Alka-Seltzer Original interact with other medicines?

Yes — aspirin interacts with several medicines, including warfarin and other anticoagulants (increased bleeding risk), methotrexate (increased toxicity), SSRIs (increased gastrointestinal bleeding risk), and other NSAIDs. Always tell your pharmacist about all medicines you are taking, including herbal remedies and supplements, before using this product.

How long can you use Alka-Seltzer Original tablets for?

Alka-Seltzer Original is intended for short-term use only — do not use for more than 3 consecutive days without consulting a pharmacist or GP. Prolonged use of aspirin increases the risk of gastrointestinal side effects, including ulcers and bleeding. If your symptoms persist beyond 3 days, seek professional medical advice.

What are the alternatives to Alka-Seltzer Original tablets?

Alternatives for pain relief include paracetamol (suitable for a wider range of people, including those who cannot take aspirin) and ibuprofen (another NSAID with anti-inflammatory properties). For indigestion alone, antacids such as calcium carbonate or magnesium trisilicate preparations are available. Speak to your pharmacist to find the most appropriate option for your specific symptoms.

Is Alka-Seltzer Original suitable for a hangover?

Alka-Seltzer Original is commonly used to relieve the symptoms of a hangover — including headache, nausea, and stomach upset — because it addresses both pain and digestive discomfort simultaneously. However, aspirin can further irritate a stomach already sensitised by alcohol, so take it with plenty of water and ideally after eating something. It is not a cure for alcohol intoxication and should not be taken before drinking.

What are the latest studies on aspirin for pain relief?

Aspirin remains a well-established analgesic supported by decades of clinical evidence, and the NHS continues to recommend it for mild-to-moderate pain in adults aged 16 and over. Recent guidance has focused on limiting long-term low-dose aspirin use in primary prevention of cardiovascular disease due to bleeding risks, but short-term use for pain relief at standard OTC doses remains appropriate for most healthy adults. Always follow current NHS and MHRA guidance when using any aspirin-containing product.

How Should You Use Alka-Seltzer Original Tablets?

Alka-Seltzer Original tablets must always be dissolved in water before you take them — never swallow them whole, chew them, or crush them. Using them correctly ensures you get the full benefit of all three active ingredients and reduces the risk of stomach irritation.

Follow these steps each time you take a dose:

What Is the Correct Dose of Alka-Seltzer Original?

The dose depends on your age and the condition you are treating. Always follow the dosage instructions on the pack and never exceed the maximum daily dose. Taking more than the recommended amount does not improve symptom relief and significantly increases the risk of side effects, particularly gastrointestinal bleeding.

When Is the Best Time to Use Alka-Seltzer Original?

Take Alka-Seltzer Original as soon as your symptoms appear — it works best when used promptly at the onset of a headache or indigestion rather than waiting until symptoms become severe. Where possible, take it with or shortly after food to help protect the stomach lining from aspirin-related irritation. Avoid taking it on a completely empty stomach, particularly if you are prone to digestive sensitivity.

If you are using it for hangover symptoms, take it after eating something and drinking plenty of water to help rehydrate at the same time.

How Long Can You Use Alka-Seltzer Original For?

Alka-Seltzer Original is designed for short-term, on-demand use only. Do not take it for more than 3 consecutive days without speaking to a pharmacist or GP. If your pain or digestive symptoms persist beyond 3 days, worsen, or keep returning, this may indicate an underlying condition that needs professional assessment rather than continued self-treatment.

Long-term or frequent use of aspirin-containing products carries an increased risk of gastrointestinal ulcers and bleeding, so it is important not to use this product as a regular daily remedy without medical supervision.

Do not exceed the recommended dose. If in doubt, speak to your pharmacist.

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What Are the Most Common Side Effects of Alka-Seltzer Original?

As with all aspirin-containing medicines, Alka-Seltzer Original can cause side effects in some people, though not everyone will experience them. The most frequently reported side effects relate to the stomach and digestive system, particularly when the tablets are taken on an empty stomach.

  • Nausea or feeling sick
  • Stomach discomfort or mild stomach pain
  • Indigestion or heartburn
  • Vomiting (less frequently)

What Are the Less Common Side Effects of Alka-Seltzer Original?

Less common side effects are more likely to occur with prolonged use or in people who have pre-existing risk factors such as a history of stomach problems. If you notice any of the following, stop taking the tablets and seek medical advice promptly.

  • Gastrointestinal bleeding — signs include black or tarry stools, or vomiting blood or material that looks like coffee grounds
  • Tinnitus (ringing or buzzing in the ears) — this can be a sign of aspirin toxicity
  • Dizziness or headache worsening rather than improving
  • Fluid retention or ankle swelling
  • Skin rash or itching

What Are the Serious Side Effects of Alka-Seltzer Original?

Serious side effects are rare but require immediate medical attention. Stop taking Alka-Seltzer Original and call 999 or go to your nearest A&E if you experience any of the following:

  • Signs of a severe allergic reaction (anaphylaxis): swelling of the face, lips, tongue, or throat; difficulty breathing; sudden drop in blood pressure; rapid heartbeat
  • Severe gastrointestinal bleeding: vomiting blood or passing black, tarry stools
  • Worsening of asthma symptoms or sudden onset of wheezing after taking the tablets
  • Signs of aspirin overdose: rapid breathing, confusion, ringing in the ears, sweating

What Should You Do If You Experience Side Effects?

For mild side effects such as nausea or stomach discomfort, try taking the dissolved solution with food or a glass of milk to help protect the stomach lining. If side effects are persistent, troublesome, or unexpected, stop taking the tablets and speak to your pharmacist or GP as soon as possible. In the case of a suspected overdose, contact the NHS 111 service or go to A&E immediately — do not wait for symptoms to worsen.

You can also report suspected side effects directly to the MHRA via the Yellow Card scheme at yellowcard.mhra.gov.uk. This helps improve medicine safety information for everyone.

Can Alka-Seltzer Original Interact With Other Medicines?

Yes — aspirin has a number of clinically significant drug interactions that you should be aware of before taking this product. The risk of interactions is higher if you are taking prescription medicines regularly. Always inform your pharmacist of all medicines you are currently taking, including over-the-counter products, herbal remedies, and supplements.

  • Warfarin and other anticoagulants — significantly increased risk of bleeding
  • Other NSAIDs (e.g. ibuprofen, naproxen) — increased risk of gastrointestinal side effects
  • Methotrexate — aspirin can reduce its excretion, increasing toxicity risk
  • SSRIs (e.g. fluoxetine, sertraline) — increased risk of gastrointestinal bleeding
  • Corticosteroids (e.g. prednisolone) — increased risk of stomach ulcers
  • Antidiabetic medicines — aspirin may enhance blood glucose-lowering effects
  • ACE inhibitors and diuretics — aspirin may reduce their effectiveness

If you are concerned about any side effects, contact your pharmacist or GP immediately.

Patient Information Leaflet

Important - Before taking any medication, it is always important to read the Patient Information Leaflet (PIL)

Written and reviewed by our qualified team

GPhC Number: 2233073
Tarun Kumar

Reviewed by:

Tarun Kumar

Superintendent/ Clinical Lead

📖 Find out more about our team of medical content authors and how we ensure the accuracy of our content with our content guidelines.

Content last updated: 31 Mar 2025

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