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Alka-Seltzer Original - 10 Effervescen Tablets (Pain Relief Migraine,Cold & Flu)

Alka-Seltzer Original - 10 Effervescen Tablets (Pain Relief Migraine,Cold & Flu)

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  • ✔️ Relieves headaches, migraines, and cold and flu aches
  • ✔️ Effervescent format dissolves fast for quicker absorption
  • ✔️ Sodium bicarbonate soothes indigestion alongside pain
  • ✔️ Contains aspirin 324mg — clinically proven analgesic
  • ✔️ Suitable for adults and young people aged 16 and over

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What Are Alka-Seltzer Original Tablets?

 

Alka-Seltzer Original tablets are a well-known over-the-counter effervescent medicine used to relieve a range of everyday symptoms — from headaches and migraines to cold and flu discomfort and indigestion. Each pack contains 10 effervescent tablets that dissolve quickly in water, making them easy to take and fast to absorb. If you're looking for a single product that tackles multiple symptoms at once, this could be a practical option to keep in your medicine cabinet. You can browse our full pain relief collection for more options suited to your needs.

Each tablet contains three active ingredients: aspirin 324mg, sodium bicarbonate 1625mg, and citric acid 965mg. Together, these work to address pain, inflammation, and excess stomach acid simultaneously. It's a combination that's been trusted in UK households for decades.

 

How Do Alka-Seltzer Original Tablets Work?

 

The mechanism behind Alka-Seltzer Original is actually quite straightforward once you understand the three ingredients. Aspirin belongs to a class of medicines called non-steroidal anti-inflammatory drugs (NSAIDs). It works by blocking enzymes called COX-1 and COX-2, which are responsible for producing prostaglandins — the chemicals that trigger pain, fever, and inflammation in the body. Sodium bicarbonate acts as an antacid, neutralising excess stomach acid and helping to reduce the gastric irritation that aspirin can sometimes cause. Citric acid reacts with the sodium bicarbonate to produce the characteristic fizzing action, which helps the tablet dissolve rapidly and may aid faster absorption.

  • Aspirin inhibits prostaglandin synthesis, reducing pain and fever
  • Sodium bicarbonate neutralises stomach acid, easing indigestion
  • Citric acid drives the effervescent reaction for rapid dissolution
  • The dissolved liquid form may be absorbed more quickly than standard solid tablets

 

Who Is Alka-Seltzer Original Suitable For?

 

Alka-Seltzer Original is intended for adults and young people aged 16 and over. It's particularly useful if you experience symptoms that overlap — for example, a headache alongside an upset stomach, or cold and flu symptoms with body aches. That said, it isn't right for everyone, and it's important to check the contraindications carefully before use.

  • Adults aged 16 and over with mild to moderate pain
  • People experiencing headaches or migraines alongside indigestion
  • Those with cold and flu symptoms including fever and body aches
  • Individuals who prefer an effervescent format over standard tablets

 

How Does Alka-Seltzer Original Compare to Standard Aspirin Tablets?

 

Feature Alka-Seltzer Original Standard Aspirin 300mg Tablets
Active ingredients Aspirin, sodium bicarbonate, citric acid Aspirin only
Formulation Effervescent (dissolved in water) Solid tablet (swallowed whole)
Indigestion relief Yes (sodium bicarbonate antacid) No
Suitable for children under 16 No No

 

How Should You Store Alka-Seltzer Original Tablets?

 

Store Alka-Seltzer Original tablets below 25°C in a dry place, away from direct sunlight and moisture. Because these are effervescent tablets, exposure to humidity can cause them to deteriorate quickly — so always keep the tube tightly sealed after opening. Keep them out of reach and sight of children at all times. If you're managing several medicines at home, it's worth checking our cold and flu collection for complementary products that may also need careful storage.

Do not use the tablets after the expiry date printed on the packaging. If the tablets have started to crumble or fizz inside the tube without being dissolved in water, they may have been exposed to moisture and should be discarded safely.

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 10 Effervescent Tablets specifications
Treatment category Pain relief, cold and flu, indigestion
Active ingredient Aspirin 324mg, Sodium Bicarbonate 1625mg, Citric Acid 965mg
Mechanism of action NSAID analgesic (aspirin) + antacid (sodium bicarbonate)
Effective for Headache, migraine, cold and flu symptoms, indigestion
Suitable for Adults and young people aged 16 and over
Pack size 10 effervescent tablets
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 10 Effervescent Tablets

 

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

 

Alka-Seltzer Original is an effervescent analgesic and antacid combination medicine available without a prescription. It is used to relieve mild to moderate pain including headaches, migraines, and the aches and pains associated with colds and flu. The sodium bicarbonate component also makes it effective for relieving the symptoms of indigestion and heartburn. Each tablet contains aspirin 324mg, sodium bicarbonate 1625mg, and citric acid 965mg — a combination that addresses both pain and gastric discomfort at the same time.

 

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

 

Before taking Alka-Seltzer Original tablets, it's essential to check whether this medicine is appropriate for you. Aspirin is not suitable for everyone, and there are several important contraindications and interactions to be aware of.

Do not take Alka-Seltzer Original if you:

  • Are under 16 years of age (risk of Reye's syndrome)
  • Are allergic to aspirin, other NSAIDs, or any ingredient in the tablet
  • Have or have had a peptic ulcer or gastrointestinal bleeding
  • Are in the third trimester of pregnancy
  • Have severe kidney, liver, or heart failure
  • Have haemophilia or another bleeding disorder

Drug interactions — tell your pharmacist if you are taking:

  • Anticoagulants such as warfarin (increased bleeding risk)
  • Methotrexate (aspirin can increase its toxicity)
  • Other NSAIDs or corticosteroids
  • Antidiabetic medicines (aspirin may affect blood glucose)
  • Medicines for gout such as probenecid
  • Selective serotonin reuptake inhibitors (SSRIs)

 

How Should You Use Alka-Seltzer Original Tablets?

 

Always use Alka-Seltzer Original exactly as directed on the packaging or as advised by your pharmacist. Never swallow the tablets whole — they must be fully dissolved in water before drinking.

  1. Fill a glass with at least 200ml (roughly a full glass) 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
Indication Age Group Dose Frequency
Headache / migraine Adults and young people 16+ 2 tablets dissolved in water Up to 4 times daily (max 8 tablets/24hrs)
Cold and flu symptoms Adults and young people 16+ 2 tablets dissolved in water Up to 4 times daily (max 8 tablets/24hrs)
Indigestion Adults and young people 16+ 2 tablets dissolved in water Up to 4 times daily (max 8 tablets/24hrs)
Children under 16 Under 16 Not suitable — do not use

If you're also managing other symptoms such as nausea alongside your cold or flu, you may find it helpful to explore our sickness and nausea collection for additional support.

 

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

 

Like all medicines, Alka-Seltzer Original can cause side effects, although not everyone will experience them. Because it contains aspirin, gastrointestinal effects are the most commonly reported. If you notice any severe or unexpected symptoms, stop taking the tablets and seek medical advice promptly.

Common side effects:

  • Nausea or stomach discomfort
  • Heartburn
  • Mild indigestion

Less common side effects:

  • Gastrointestinal bleeding (black or tarry stools — seek urgent medical attention)
  • Allergic reactions including skin rash, itching, or swelling
  • Bronchospasm (wheezing or difficulty breathing), particularly in people with asthma
  • Tinnitus (ringing in the ears) at higher doses

 

How Should You Store Alka-Seltzer Original Tablets?

 

Correct storage is particularly important for effervescent tablets, as moisture can cause them to degrade before use. For general health product storage guidance, it's also worth checking our vitamins and supplements collection, where similar storage principles apply.

  • Store below 25°C in a dry place
  • Keep away from direct sunlight and sources of heat
  • Always replace the cap firmly after removing a tablet
  • Keep out of reach and sight of children
  • Do not use after the expiry date printed on the packaging
  • Do not store in a bathroom or near a sink — humidity will damage the tablets

Written and reviewed by our qualified team

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 for just £3.95 per pack of 10 effervescent tablets. They are available without a prescription as an over-the-counter medicine. No appointment or GP referral is needed — simply add to your basket and order directly from our pain relief collection.

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

Alka-Seltzer Original tablets contain aspirin, which blocks COX enzymes to reduce the production of prostaglandins — the chemicals responsible for pain, fever, and inflammation. Sodium bicarbonate neutralises excess stomach acid, helping to ease indigestion and reduce the gastric irritation that aspirin can sometimes cause. Citric acid drives the effervescent reaction, helping the tablet dissolve rapidly so the active ingredients are absorbed quickly.

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

Drop 2 tablets into a full glass of water (at least 200ml) and wait until they have completely dissolved before drinking the solution. Never swallow the tablets whole or chew them. Repeat every 4 hours if needed, but do not take more than 8 tablets in any 24-hour period.

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

The standard adult dose is 2 tablets dissolved in at least 200ml of water, taken up to 4 times daily. Each dose should be spaced at least 4 hours apart, and you must not exceed 8 tablets in 24 hours. If your symptoms persist beyond 3 days, speak to your pharmacist or GP.

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

Alka-Seltzer Original can be taken at any time of day when symptoms arise — there is no fixed optimal time. Taking it with or after food may help reduce the risk of stomach irritation, even though the sodium bicarbonate already provides some gastric protection. Avoid taking a dose too close to bedtime unless necessary, as lying down shortly after can sometimes worsen heartburn.

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

Common side effects include nausea, stomach discomfort, and heartburn. Less commonly, some people may experience gastrointestinal bleeding (indicated by black or tarry stools), allergic reactions such as skin rash or swelling, or bronchospasm in people with asthma. If you experience any severe or unexpected symptoms, stop taking the tablets and seek medical advice promptly.

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

If you experience mild stomach discomfort, try taking the dissolved solution with or after a meal. For persistent nausea or heartburn, speak to your pharmacist — they may suggest an alternative pain reliever such as paracetamol that is gentler on the stomach. Stop taking the tablets immediately and seek urgent medical attention if you notice signs of gastrointestinal bleeding, such as vomiting blood or passing black stools.

Who should not take Alka-Seltzer Original tablets?

Alka-Seltzer Original is not suitable for children under 16 years of age due to the risk of Reye's syndrome, a rare but serious condition associated with aspirin use in children. It should also be avoided by people who are allergic to aspirin or other NSAIDs, those with active peptic ulcers or a history of gastrointestinal bleeding, and women in the third trimester of pregnancy. People with severe kidney, liver, or heart failure should also not use this product.

Can I take Alka-Seltzer Original tablets for a migraine?

Yes, Alka-Seltzer Original tablets can be used to relieve mild to moderate migraine headache pain. The aspirin component provides analgesic and anti-inflammatory effects, and the effervescent formulation may allow faster absorption compared to standard solid tablets. If your migraines are frequent, severe, or not responding to over-the-counter treatment, speak to your GP for further assessment.

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

Aspirin and other NSAIDs can trigger bronchospasm in some people with asthma, so Alka-Seltzer Original should be used with caution if you have this condition. If you have previously experienced wheezing or breathing difficulties after taking aspirin or ibuprofen, you should not use this product. Speak to your GP or pharmacist before taking it if you have asthma and are unsure whether it is safe for you.

What happens if I miss a dose of Alka-Seltzer Original?

Alka-Seltzer Original is taken as needed for symptom relief rather than on a fixed schedule, so there is no concept of a "missed dose" in the traditional sense. Simply take a dose when your symptoms return, provided at least 4 hours have passed since your last dose. Never double up doses to compensate for a missed one.

Can I take Alka-Seltzer Original with other medicines?

Alka-Seltzer Original can interact with several medicines, including anticoagulants like warfarin, methotrexate, other NSAIDs, antidiabetic medicines, and SSRIs. Always tell your pharmacist about all medicines you are currently taking — including herbal remedies and supplements — before using this product. If you are on regular prescribed medication, it is advisable to check with your GP or pharmacist first.

What are the alternatives to Alka-Seltzer Original tablets?

If Alka-Seltzer Original is not suitable for you, alternatives for pain relief include paracetamol or ibuprofen, depending on your symptoms and medical history. For cold and flu symptoms specifically, you may also find useful options in our cold and flu collection. Always speak to a pharmacist if you are unsure which product is most appropriate for your situation.

How long can I keep taking Alka-Seltzer Original tablets?

Alka-Seltzer Original is intended for short-term use only. For pain relief, you should not use it for more than 3 consecutive days without speaking to a pharmacist or GP. If your symptoms persist, worsen, or keep returning, it is important to seek professional medical advice rather than continuing to self-medicate.

What are the latest studies on aspirin for headache and migraine relief?

Aspirin has been studied extensively as a first-line treatment for mild to moderate migraine, and clinical evidence supports its effectiveness at doses of 900–1000mg — higher than the standard Alka-Seltzer dose. The NHS acknowledges aspirin as one of the recommended over-the-counter options for migraine relief. If you find over-the-counter aspirin insufficient for your migraines, your GP can discuss prescription-strength options with you.

How Should You Use Alka-Seltzer Original Tablets?

Alka-Seltzer Original tablets must always be dissolved in water before taking — never swallow them whole or chew them. The effervescent action is part of how the medicine works, so it's important to wait until the fizzing has completely stopped before drinking the solution.

Follow these steps each time you take a dose:

What Is the Correct Dose of Alka-Seltzer Original?

The dose depends on the symptom being treated, but the standard adult dose is 2 tablets per occasion. Always leave at least 4 hours between doses and never exceed 8 tablets in any 24-hour period. This product is not suitable for children under 16 years of age.

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

Take Alka-Seltzer Original as soon as your symptoms begin — early use tends to be more effective, particularly for headaches and migraines. Taking the dissolved solution with or after food may help reduce the risk of stomach irritation, even though the sodium bicarbonate already provides some gastric buffering.

Avoid taking a dose immediately before lying down, as this can sometimes worsen heartburn. If you are using it for cold and flu symptoms, spacing doses evenly throughout the day will help maintain consistent symptom relief.

How Long Can You Use Alka-Seltzer Original For?

Alka-Seltzer Original is designed for short-term, symptomatic relief only. For pain relief, do not use it for more than 3 consecutive days without consulting a pharmacist or GP. If your symptoms persist beyond this period, worsen, or keep recurring, you should seek professional medical advice rather than continuing to self-treat.

Long-term or frequent use of aspirin-containing products without medical supervision is not recommended, as it can increase the risk of gastrointestinal side effects including bleeding. If you find yourself needing pain relief regularly, speak to your GP to identify and address the underlying cause.

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

How Should You Use Alka-Seltzer Original Tablets?

Alka-Seltzer Original tablets must always be dissolved in water before taking — never swallow them whole or chew them. The effervescent action is part of how the medicine works, so it's important to wait until the fizzing has completely stopped before drinking the solution.

Follow these steps each time you take a dose:

What Is the Correct Dose of Alka-Seltzer Original?

The dose depends on the symptom being treated, but the standard adult dose is 2 tablets per occasion. Always leave at least 4 hours between doses and never exceed 8 tablets in any 24-hour period. This product is not suitable for children under 16 years of age.

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

Take Alka-Seltzer Original as soon as your symptoms begin — early use tends to be more effective, particularly for headaches and migraines. Taking the dissolved solution with or after food may help reduce the risk of stomach irritation, even though the sodium bicarbonate already provides some gastric buffering.

Avoid taking a dose immediately before lying down, as this can sometimes worsen heartburn. If you are using it for cold and flu symptoms, spacing doses evenly throughout the day will help maintain consistent symptom relief.

How Long Can You Use Alka-Seltzer Original For?

Alka-Seltzer Original is designed for short-term, symptomatic relief only. For pain relief, do not use it for more than 3 consecutive days without consulting a pharmacist or GP. If your symptoms persist beyond this period, worsen, or keep recurring, you should seek professional medical advice rather than continuing to self-treat.

Long-term or frequent use of aspirin-containing products without medical supervision is not recommended, as it can increase the risk of gastrointestinal side effects including bleeding. If you find yourself needing pain relief regularly, speak to your GP to identify and address the underlying cause.

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?

Because Alka-Seltzer Original contains aspirin — an NSAID — the most frequently reported side effects relate to the gastrointestinal tract. Most people tolerate the medicine well when taken as directed, but it's worth knowing what to look out for.

  • Nausea or feeling sick
  • Stomach discomfort or cramping
  • Heartburn
  • Mild indigestion

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

Less commonly, some people may experience more noticeable reactions. These are not typical but are worth being aware of, particularly if you are taking Alka-Seltzer Original for the first time or using it alongside other medicines.

  • Tinnitus (ringing or buzzing in the ears), particularly at higher doses
  • Dizziness or light-headedness
  • Skin rash or itching
  • Swelling of the face, lips, or throat (angioedema)
  • Worsening of indigestion symptoms

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

Serious side effects are uncommon but require immediate medical attention if they occur. Aspirin can irritate the lining of the stomach and, in some cases, cause gastrointestinal bleeding — particularly with prolonged use or in people with a history of stomach problems.

Seek urgent medical help if you notice any of the following:

  • Vomiting blood or material that looks like coffee grounds
  • Black, tarry, or bloody stools — a sign of gastrointestinal bleeding
  • Severe allergic reaction (anaphylaxis): sudden swelling, difficulty breathing, or collapse
  • Bronchospasm: sudden wheezing or chest tightness, especially in people with asthma

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 or after food. If symptoms are persistent or troublesome, stop taking the tablets and speak to your pharmacist — they may recommend an alternative pain reliever such as paracetamol that is less likely to irritate the stomach.

For any serious side effects — particularly signs of bleeding or a severe allergic reaction — stop taking the medicine immediately and call 999 or go to your nearest A&E department. Do not wait to see if symptoms improve on their own.

Can Alka-Seltzer Original Interact With Other Medicines?

Yes. Aspirin interacts with a number of commonly prescribed medicines, and some interactions can be clinically significant. Always inform your pharmacist or GP about all medicines you are taking before using Alka-Seltzer Original, including over-the-counter products and herbal supplements.

Key interactions to be aware of include anticoagulants such as warfarin (increased bleeding risk), methotrexate (aspirin can increase its toxicity), other NSAIDs or corticosteroids (increased gastrointestinal risk), SSRIs (increased bleeding risk), and antidiabetic medicines (aspirin may affect blood glucose levels). The high sodium content of the tablets may also be relevant for people on sodium-restricted diets or those with heart failure or hypertension.

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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