Alka-Seltzer XS Tablets 324mg/965mg/1625mg – 20 Tablets

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What Are Alka-Seltzer XS Tablets Used For?
For those occasions when standard pain relief feels insufficient — a persistent or severe headache, the full force of a cold or flu, or the compound discomfort of a hangover — Alka-Seltzer XS Effervescent Tablets offer a step up in analgesic power whilst retaining the fast-dissolving, easy-on-the-stomach effervescent format that has made the Alka-Seltzer range a household name. The XS formulation combines three synergistic active ingredients in a single dissolving tablet, providing enhanced pain relief compared with either aspirin or paracetamol used alone.
Alka-Seltzer XS contains aspirin, paracetamol, and caffeine as its active ingredients, delivered in an effervescent, buffered formulation. Aspirin is a well-established NSAID analgesic and antipyretic that inhibits prostaglandin synthesis to relieve pain and reduce fever. Paracetamol provides complementary analgesic and antipyretic action through a different mechanism, and the combination of the two analgesics is recognised clinically to provide greater pain relief than either alone at standard doses. Caffeine acts as an analgesic adjuvant — it does not relieve pain directly but has been shown in clinical studies to enhance the effectiveness of aspirin and paracetamol when combined with them, allowing effective pain relief to be achieved with lower doses of each analgesic than would be needed individually. The effervescent base includes sodium bicarbonate, which provides antacid activity and buffers the aspirin, reducing its potential for gastric irritation and simultaneously helping to relieve any associated stomach discomfort.
Alka-Seltzer XS is suitable for adults and young people aged 16 and over. As with all aspirin-containing products, it must not be given to anyone under 16 due to the risk of Reye's syndrome. Those taking other paracetamol-containing products must take particular care not to exceed the safe total daily dose of paracetamol across all products being used. This is a critical safety point — paracetamol overdose causes serious liver damage that may not be immediately apparent. If you are unsure whether any other medicine you take contains paracetamol, ask your Pearl Chemist Group pharmacist before using Alka-Seltzer XS.
For personalised advice on the most appropriate pain relief for your symptoms, speak to a Pearl Chemist Group pharmacist, or browse our full pain relief range.
How to Use Alka-Seltzer XS Tablets
- Fill a full glass with plain water. Use at least 200ml of still water at room temperature or cool. Do not use hot water, fruit juice, or other drinks.
- Drop 2 tablets into the water. Remove 2 tablets from the foil blister and drop them simultaneously into the glass.
- Wait for complete dissolution. Allow the tablets to dissolve fully and the fizzing to subside before drinking — approximately one to two minutes.
- Drink the entire solution. Consume the full contents of the glass once dissolution is complete.
- Repeat every 4 hours if needed. Do not take more than the stated maximum number of doses in 24 hours (verify from PIL).
Critical safety checks before each dose
- Confirm that no other paracetamol-containing medicine has been taken since the last dose.
- Do not take with alcohol — this significantly increases the risk of gastrointestinal bleeding from aspirin and liver toxicity from paracetamol.
- Store remaining tablets in their sealed foil blisters to prevent moisture damage.
Alka-Seltzer XS Tablets Side Effects
Side effects relate to the aspirin, paracetamol, and caffeine components of the formulation.
Common side effects (may affect more than 1 in 10 people)
- Nausea or mild stomach discomfort — reduced by the buffered effervescent formulation
- Mild stimulant effects from the caffeine component, such as slight restlessness or difficulty sleeping if taken late in the day
Less common side effects (may affect between 1 in 10 and 1 in 100 people)
- Heartburn or indigestion
- Increased bleeding tendency from the aspirin component
- Palpitations or increased heart rate in those sensitive to caffeine
Rare side effects (may affect fewer than 1 in 100 people)
- Gastrointestinal ulceration or bleeding
- Tinnitus — may indicate aspirin toxicity
- Bronchospasm in aspirin-sensitive individuals
- Liver damage — only with overdose or concurrent use of other paracetamol products; does not occur at recommended doses in healthy individuals
- Skin rash or allergic reaction
Stop using and seek urgent medical help if you experience:
- Black or tarry stools, vomiting blood, or severe stomach pain
- Tinnitus
- Worsening breathing or a severe asthma attack
- Any concern about paracetamol overdose — call 999 or NHS 111 immediately
- Signs of a serious allergic reaction — call 999 immediately
Report any unexpected reaction via the MHRA Yellow Card scheme at yellowcard.mhra.gov.uk or speak to your Pearl Chemist Group pharmacist.
How to Store Alka-Seltzer XS Tablets
- Temperature: Store below 25°C in a dry place. Moisture will cause premature effervescent reaction and render tablets unusable.
- Packaging: Keep in original sealed foil blisters until immediately before use.
- Do not refrigerate.
- Children: Keep out of the sight and reach of children at all times.
- Expiry: Do not use after the expiry date on the blister and outer carton.
- Disposal: Return unused tablets to your Pearl Chemist Group pharmacy for safe disposal.
Who Are Alka-Seltzer XS Tablets Suitable For?
Alka-Seltzer XS Effervescent Tablets are suitable for adults and young people aged 16 and over who experience moderate to moderately severe headache, cold and flu symptoms, or other painful conditions and who wish to use a combined analgesic preparation with enhanced pain-relieving effect.
Suitable for:
- Adults with headache, migraine headache, dental pain, period pain, or muscle pain
- Those experiencing the symptoms of colds and influenza, including headache, aches, and fever
- People experiencing hangover-related headache and stomach discomfort
- Young people aged 16 to 17 under appropriate adult supervision
- Those who find single-ingredient analgesics insufficient for their pain
Not suitable for — do not use if you:
- Are under 16 years of age — aspirin must never be given to children and young people under 16
- Have a known allergy to aspirin, paracetamol, caffeine, salicylates, or other NSAIDs
- Have an active peptic ulcer or significant gastrointestinal bleeding history
- Have severe liver disease or are a heavy regular alcohol user — paracetamol is particularly dangerous in these circumstances
- Have haemophilia or any other bleeding disorder
- Are in the third trimester of pregnancy
- Are already taking any other paracetamol-containing product — do not exceed the total safe daily dose of paracetamol of 4g (4000mg) across all products
Use with caution or seek advice first if you:
- Take anticoagulants such as warfarin
- Have asthma that may be aspirin-sensitive
- Are on a sodium-restricted diet
- Are sensitive to caffeine or wish to limit caffeine intake
- Are pregnant in the first or second trimester, or breastfeeding
- Are elderly, or have kidney or liver impairment
Our Pearl Chemist Group pharmacists can help you confirm whether Alka-Seltzer XS is the most appropriate pain relief option for you.
Active Ingredients in Alka-Seltzer XS Tablets
Important note: The active ingredient strengths below are based on the best available product data but must be verified against the current patient information leaflet enclosed in the physical pack before this page is published. The declared pack strengths of 324mg/965mg/1625mg should be confirmed with the manufacturer or PIL.
| Ingredient | Approximate strength per tablet | Role |
|---|---|---|
| Aspirin (acetylsalicylic acid) | 267mg (please verify) | NSAID analgesic and antipyretic. Inhibits COX enzymes and reduces prostaglandin synthesis to relieve pain and reduce fever. Works synergistically with paracetamol to provide greater combined analgesic effect than either ingredient alone at these doses. |
| Paracetamol | 133mg (please verify) | Complementary analgesic and antipyretic with a different mechanism of action from aspirin. Contributes to the combined pain-relieving effect and helps to reduce fever. Paracetamol is particularly important for those in whom higher aspirin doses alone would not be well tolerated. |
| Caffeine | 40mg (please verify) | An analgesic adjuvant that does not relieve pain directly but significantly enhances the effectiveness of aspirin and paracetamol when combined with them. Well-established clinical evidence supports caffeine's role in improving the pain-relieving performance of combined analgesic preparations. Also provides mild stimulant activity which may help with the fatigue associated with headache, cold, and flu symptoms. |
| Sodium bicarbonate (buffer/antacid) | Please verify from PIL | Provides the effervescent action together with the citric acid component and delivers antacid activity, buffering the aspirin and reducing gastric irritation. Also helps relieve indigestion or stomach upset accompanying the primary symptoms. |
Alka-Seltzer XS Tablets Dosage — How Much to Take
Note: Verify the exact dosage from the PIL enclosed in the physical pack before publication. The figures below are based on best available data.
Adults and young people aged 16 and over
- Dose: 2 tablets dissolved in a full glass of water (at least 200ml).
- Frequency: Every 4 hours as needed.
- Maximum daily dose: 6 tablets (3 doses) in any 24-hour period — please verify from PIL.
- How to take: Drop tablets into water, wait for complete dissolution, then drink the entire solution.
Children and young people under 16
Do not give to anyone under 16 years of age.
Critical paracetamol warning
Do not take Alka-Seltzer XS alongside any other product containing paracetamol. Taking more than one paracetamol-containing product at the same time can lead to a total daily dose that causes serious and potentially irreversible liver damage. This is a medical emergency that may not produce obvious symptoms until significant damage has already occurred. If you are unsure whether any other medicine you take contains paracetamol, consult your pharmacist before using this product.
Elderly patients
Use with caution. The aspirin component poses an increased risk of gastrointestinal bleeding in elderly patients. Use the lowest effective dose for the shortest necessary period and seek pharmacist or GP advice before regular use.
Precautions When Using Alka-Seltzer XS Tablets
Before use
- Check that you are not taking any other paracetamol-containing product — this is the most critical safety check for Alka-Seltzer XS.
- Confirm no aspirin or paracetamol allergy.
- Check the expiry date and that foil blisters are intact.
- Do not use if you have consumed significant amounts of alcohol.
- Do not give to anyone under 16.
During use
- Always fully dissolve tablets before drinking.
- Do not take with alcohol.
- Do not exceed the stated maximum daily dose.
- Do not combine with other paracetamol, aspirin, or NSAID-containing products.
Duration of use
- Do not use for more than 3 days for pain or fever without seeking pharmacist or GP guidance.
When to seek urgent medical advice
- If you suspect a paracetamol overdose — seek emergency medical help immediately even if you feel well, as liver damage develops without early symptoms.
- Black or tarry stools, vomiting blood, or severe stomach pain.
- Tinnitus or sudden hearing change.
- Signs of a serious allergic reaction — call 999 immediately.
Our Pearl Chemist Group pharmacists are available for free guidance on safe pain relief management.
Full Ingredients in Alka-Seltzer XS Tablets
Active ingredient strengths must be verified against the PIL enclosed in the physical pack before publication. The figures below are approximate and based on best available data.
Active ingredients per tablet (approximate — please verify): aspirin approximately 267mg, paracetamol approximately 133mg, caffeine approximately 40mg, plus sodium bicarbonate and citric acid in the effervescent buffer base.
This product contains a significant amount of sodium per dose from the effervescent buffer. Those on medically supervised sodium-restricted diets should consult their pharmacist before use.
If you have any concern about any ingredient, speak to a Pearl Chemist Group pharmacist before use.
Last reviewed: May 2026. Active ingredient strengths to be confirmed from PIL before publication.
Always read the patient information leaflet before use. A copy is included in the pack. For advice, speak to a Pearl Chemist pharmacist or call +44 (0)20 8672 2157.
What Are Alka-Seltzer XS Tablets Used For?
For those occasions when standard pain relief feels insufficient — a persistent or severe headache, the full force of a cold or flu, or the compound discomfort of a hangover — Alka-Seltzer XS Effervescent Tablets offer a step up in analgesic power whilst retaining the fast-dissolving, easy-on-the-stomach effervescent format that has made the Alka-Seltzer range a household name. The XS formulation combines three synergistic active ingredients in a single dissolving tablet, providing enhanced pain relief compared with either aspirin or paracetamol used alone.
Alka-Seltzer XS contains aspirin, paracetamol, and caffeine as its active ingredients, delivered in an effervescent, buffered formulation. Aspirin is a well-established NSAID analgesic and antipyretic that inhibits prostaglandin synthesis to relieve pain and reduce fever. Paracetamol provides complementary analgesic and antipyretic action through a different mechanism, and the combination of the two analgesics is recognised clinically to provide greater pain relief than either alone at standard doses. Caffeine acts as an analgesic adjuvant — it does not relieve pain directly but has been shown in clinical studies to enhance the effectiveness of aspirin and paracetamol when combined with them, allowing effective pain relief to be achieved with lower doses of each analgesic than would be needed individually. The effervescent base includes sodium bicarbonate, which provides antacid activity and buffers the aspirin, reducing its potential for gastric irritation and simultaneously helping to relieve any associated stomach discomfort.
Alka-Seltzer XS is suitable for adults and young people aged 16 and over. As with all aspirin-containing products, it must not be given to anyone under 16 due to the risk of Reye's syndrome. Those taking other paracetamol-containing products must take particular care not to exceed the safe total daily dose of paracetamol across all products being used. This is a critical safety point — paracetamol overdose causes serious liver damage that may not be immediately apparent. If you are unsure whether any other medicine you take contains paracetamol, ask your Pearl Chemist Group pharmacist before using Alka-Seltzer XS.
For personalised advice on the most appropriate pain relief for your symptoms, speak to a Pearl Chemist Group pharmacist, or browse our full pain relief range.
How to Use Alka-Seltzer XS Tablets
- Fill a full glass with plain water. Use at least 200ml of still water at room temperature or cool. Do not use hot water, fruit juice, or other drinks.
- Drop 2 tablets into the water. Remove 2 tablets from the foil blister and drop them simultaneously into the glass.
- Wait for complete dissolution. Allow the tablets to dissolve fully and the fizzing to subside before drinking — approximately one to two minutes.
- Drink the entire solution. Consume the full contents of the glass once dissolution is complete.
- Repeat every 4 hours if needed. Do not take more than the stated maximum number of doses in 24 hours (verify from PIL).
Critical safety checks before each dose
- Confirm that no other paracetamol-containing medicine has been taken since the last dose.
- Do not take with alcohol — this significantly increases the risk of gastrointestinal bleeding from aspirin and liver toxicity from paracetamol.
- Store remaining tablets in their sealed foil blisters to prevent moisture damage.
Alka-Seltzer XS Tablets Side Effects
Side effects relate to the aspirin, paracetamol, and caffeine components of the formulation.
Common side effects (may affect more than 1 in 10 people)
- Nausea or mild stomach discomfort — reduced by the buffered effervescent formulation
- Mild stimulant effects from the caffeine component, such as slight restlessness or difficulty sleeping if taken late in the day
Less common side effects (may affect between 1 in 10 and 1 in 100 people)
- Heartburn or indigestion
- Increased bleeding tendency from the aspirin component
- Palpitations or increased heart rate in those sensitive to caffeine
Rare side effects (may affect fewer than 1 in 100 people)
- Gastrointestinal ulceration or bleeding
- Tinnitus — may indicate aspirin toxicity
- Bronchospasm in aspirin-sensitive individuals
- Liver damage — only with overdose or concurrent use of other paracetamol products; does not occur at recommended doses in healthy individuals
- Skin rash or allergic reaction
Stop using and seek urgent medical help if you experience:
- Black or tarry stools, vomiting blood, or severe stomach pain
- Tinnitus
- Worsening breathing or a severe asthma attack
- Any concern about paracetamol overdose — call 999 or NHS 111 immediately
- Signs of a serious allergic reaction — call 999 immediately
Report any unexpected reaction via the MHRA Yellow Card scheme at yellowcard.mhra.gov.uk or speak to your Pearl Chemist Group pharmacist.
How to Store Alka-Seltzer XS Tablets
- Temperature: Store below 25°C in a dry place. Moisture will cause premature effervescent reaction and render tablets unusable.
- Packaging: Keep in original sealed foil blisters until immediately before use.
- Do not refrigerate.
- Children: Keep out of the sight and reach of children at all times.
- Expiry: Do not use after the expiry date on the blister and outer carton.
- Disposal: Return unused tablets to your Pearl Chemist Group pharmacy for safe disposal.
Who Are Alka-Seltzer XS Tablets Suitable For?
Alka-Seltzer XS Effervescent Tablets are suitable for adults and young people aged 16 and over who experience moderate to moderately severe headache, cold and flu symptoms, or other painful conditions and who wish to use a combined analgesic preparation with enhanced pain-relieving effect.
Suitable for:
- Adults with headache, migraine headache, dental pain, period pain, or muscle pain
- Those experiencing the symptoms of colds and influenza, including headache, aches, and fever
- People experiencing hangover-related headache and stomach discomfort
- Young people aged 16 to 17 under appropriate adult supervision
- Those who find single-ingredient analgesics insufficient for their pain
Not suitable for — do not use if you:
- Are under 16 years of age — aspirin must never be given to children and young people under 16
- Have a known allergy to aspirin, paracetamol, caffeine, salicylates, or other NSAIDs
- Have an active peptic ulcer or significant gastrointestinal bleeding history
- Have severe liver disease or are a heavy regular alcohol user — paracetamol is particularly dangerous in these circumstances
- Have haemophilia or any other bleeding disorder
- Are in the third trimester of pregnancy
- Are already taking any other paracetamol-containing product — do not exceed the total safe daily dose of paracetamol of 4g (4000mg) across all products
Use with caution or seek advice first if you:
- Take anticoagulants such as warfarin
- Have asthma that may be aspirin-sensitive
- Are on a sodium-restricted diet
- Are sensitive to caffeine or wish to limit caffeine intake
- Are pregnant in the first or second trimester, or breastfeeding
- Are elderly, or have kidney or liver impairment
Our Pearl Chemist Group pharmacists can help you confirm whether Alka-Seltzer XS is the most appropriate pain relief option for you.
Active Ingredients in Alka-Seltzer XS Tablets
Important note: The active ingredient strengths below are based on the best available product data but must be verified against the current patient information leaflet enclosed in the physical pack before this page is published. The declared pack strengths of 324mg/965mg/1625mg should be confirmed with the manufacturer or PIL.
| Ingredient | Approximate strength per tablet | Role |
|---|---|---|
| Aspirin (acetylsalicylic acid) | 267mg (please verify) | NSAID analgesic and antipyretic. Inhibits COX enzymes and reduces prostaglandin synthesis to relieve pain and reduce fever. Works synergistically with paracetamol to provide greater combined analgesic effect than either ingredient alone at these doses. |
| Paracetamol | 133mg (please verify) | Complementary analgesic and antipyretic with a different mechanism of action from aspirin. Contributes to the combined pain-relieving effect and helps to reduce fever. Paracetamol is particularly important for those in whom higher aspirin doses alone would not be well tolerated. |
| Caffeine | 40mg (please verify) | An analgesic adjuvant that does not relieve pain directly but significantly enhances the effectiveness of aspirin and paracetamol when combined with them. Well-established clinical evidence supports caffeine's role in improving the pain-relieving performance of combined analgesic preparations. Also provides mild stimulant activity which may help with the fatigue associated with headache, cold, and flu symptoms. |
| Sodium bicarbonate (buffer/antacid) | Please verify from PIL | Provides the effervescent action together with the citric acid component and delivers antacid activity, buffering the aspirin and reducing gastric irritation. Also helps relieve indigestion or stomach upset accompanying the primary symptoms. |
Alka-Seltzer XS Tablets Dosage — How Much to Take
Note: Verify the exact dosage from the PIL enclosed in the physical pack before publication. The figures below are based on best available data.
Adults and young people aged 16 and over
- Dose: 2 tablets dissolved in a full glass of water (at least 200ml).
- Frequency: Every 4 hours as needed.
- Maximum daily dose: 6 tablets (3 doses) in any 24-hour period — please verify from PIL.
- How to take: Drop tablets into water, wait for complete dissolution, then drink the entire solution.
Children and young people under 16
Do not give to anyone under 16 years of age.
Critical paracetamol warning
Do not take Alka-Seltzer XS alongside any other product containing paracetamol. Taking more than one paracetamol-containing product at the same time can lead to a total daily dose that causes serious and potentially irreversible liver damage. This is a medical emergency that may not produce obvious symptoms until significant damage has already occurred. If you are unsure whether any other medicine you take contains paracetamol, consult your pharmacist before using this product.
Elderly patients
Use with caution. The aspirin component poses an increased risk of gastrointestinal bleeding in elderly patients. Use the lowest effective dose for the shortest necessary period and seek pharmacist or GP advice before regular use.
Precautions When Using Alka-Seltzer XS Tablets
Before use
- Check that you are not taking any other paracetamol-containing product — this is the most critical safety check for Alka-Seltzer XS.
- Confirm no aspirin or paracetamol allergy.
- Check the expiry date and that foil blisters are intact.
- Do not use if you have consumed significant amounts of alcohol.
- Do not give to anyone under 16.
During use
- Always fully dissolve tablets before drinking.
- Do not take with alcohol.
- Do not exceed the stated maximum daily dose.
- Do not combine with other paracetamol, aspirin, or NSAID-containing products.
Duration of use
- Do not use for more than 3 days for pain or fever without seeking pharmacist or GP guidance.
When to seek urgent medical advice
- If you suspect a paracetamol overdose — seek emergency medical help immediately even if you feel well, as liver damage develops without early symptoms.
- Black or tarry stools, vomiting blood, or severe stomach pain.
- Tinnitus or sudden hearing change.
- Signs of a serious allergic reaction — call 999 immediately.
Our Pearl Chemist Group pharmacists are available for free guidance on safe pain relief management.
Full Ingredients in Alka-Seltzer XS Tablets
Active ingredient strengths must be verified against the PIL enclosed in the physical pack before publication. The figures below are approximate and based on best available data.
Active ingredients per tablet (approximate — please verify): aspirin approximately 267mg, paracetamol approximately 133mg, caffeine approximately 40mg, plus sodium bicarbonate and citric acid in the effervescent buffer base.
This product contains a significant amount of sodium per dose from the effervescent buffer. Those on medically supervised sodium-restricted diets should consult their pharmacist before use.
If you have any concern about any ingredient, speak to a Pearl Chemist Group pharmacist before use.
Last reviewed: May 2026. Active ingredient strengths to be confirmed from PIL before publication.
Always read the patient information leaflet before use. A copy is included in the pack. For advice, speak to a Pearl Chemist pharmacist or call +44 (0)20 8672 2157.
FAQs
Alka-Seltzer XS contains three active ingredients — aspirin, paracetamol, and caffeine — whereas Alka-Seltzer Original contains only aspirin (plus the antacid buffer). The combination of two analgesics with complementary mechanisms of action provides greater pain relief than either alone at these doses, and the caffeine further enhances their effectiveness as a recognised analgesic adjuvant. Alka-Seltzer XS is therefore more appropriate for more intense or stubborn pain where standard single-ingredient relief has proved insufficient.
Paracetamol is found in a very large number of over-the-counter and prescribed medicines — cold and flu remedies, combination pain relief tablets, and many others. Taking Alka-Seltzer XS at the same time as any other product containing paracetamol can easily lead to a total daily paracetamol dose that causes serious and irreversible liver damage. This damage can develop silently, without obvious symptoms, in the first 24 hours. If you are in any doubt about whether another medicine you are taking contains paracetamol, ask your Pearl Chemist Group pharmacist before using Alka-Seltzer XS.
The caffeine content per tablet in Alka-Seltzer XS is relatively low — approximately 40mg per tablet — broadly comparable to a small cup of tea. Most people tolerate this without difficulty. However, if you are particularly sensitive to caffeine, are trying to limit your caffeine intake, or are taking the tablets late in the evening, the caffeine content may contribute to mild restlessness or difficulty sleeping. Those with conditions aggravated by caffeine should consult their pharmacist before use.
Alka-Seltzer XS is specifically associated with hangover relief in its marketing heritage, and its combination of aspirin for headache, an antacid for stomach discomfort, and caffeine for alertness does address several hangover symptoms. However, it is important to note that alcohol increases the risk of gastrointestinal irritation from aspirin and the risk of liver stress from paracetamol. If you have consumed a substantial amount of alcohol, allow time for the alcohol to clear your system and drink plenty of water before using Alka-Seltzer XS. Do not take alongside other paracetamol products.
No, not without specific medical advice. Aspirin significantly enhances the anticoagulant effect of warfarin and substantially increases the risk of serious bleeding. If you take warfarin or any other anticoagulant, do not use Alka-Seltzer XS or any aspirin-containing product without first consulting your GP or pharmacist. There are aspirin-free analgesic options available that do not carry this interaction risk.
Alka-Seltzer XS contains aspirin, which must never be given to children and young people under 16 years of age due to the risk of Reye's syndrome — a rare but potentially fatal condition affecting the brain and liver that has been associated with aspirin use in this age group. For pain and fever relief in those under 16, paracetamol-based or ibuprofen-based products (where age-appropriate) are safe and effective alternatives.