Adults under 60 can take up to 8 Alka-Seltzer Original tablets in 24 hours. Adults 60 and older should take no more than 4 tablets in 24 hours. The standard dose is 2 tablets dissolved in water every 4 hours as needed.
Dosing Schedule for Adults
Each dose of Alka-Seltzer Original is 2 tablets dissolved in a glass of water. You can repeat that dose every 4 hours, but the daily ceiling depends on your age:
- Adults and children 12 and over: no more than 8 tablets (4 doses) in 24 hours
- Adults 60 and over: no more than 4 tablets (2 doses) in 24 hours
- Children under 12: not recommended without a doctor’s guidance
The lower limit for older adults exists because the risk of serious stomach bleeding from aspirin rises significantly after age 60.
What’s Actually in Each Tablet
Every Alka-Seltzer Original tablet contains 325 mg of aspirin and 567 mg of sodium. That matters more than most people realize. If you take the full 8 tablets allowed for younger adults, you’re consuming 2,600 mg of aspirin and over 4,500 mg of sodium in a single day. For context, the American Heart Association recommends staying under 2,300 mg of sodium daily, and ideally closer to 1,500 mg. Even 4 tablets puts you past 2,200 mg of sodium from Alka-Seltzer alone, before counting anything you eat or drink.
If you’re on a sodium-restricted diet or managing high blood pressure, this sodium load is worth paying attention to.
Heartburn Relief vs. Original Formula
Alka-Seltzer Heartburn Relief Extra Strength has the same dosing limits: up to 8 tablets per day for adults under 60, and up to 4 tablets for those 60 and older, taken 2 at a time every 4 hours. The key difference is that the Heartburn Relief formula does not contain aspirin, so it doesn’t carry the same stomach bleeding risk. If you’re reaching for Alka-Seltzer purely for heartburn rather than pain, the Heartburn Relief version avoids the aspirin issue entirely.
Stomach Bleeding Risk
The FDA has issued a specific warning about aspirin-containing antacid products like Alka-Seltzer Original. The combination of aspirin and the fizzy, fast-dissolving delivery can irritate the stomach lining, and some people are more vulnerable than others. Your risk of serious bleeding is higher if you:
- Are 60 or older
- Have a history of stomach ulcers or bleeding problems
- Take blood thinners
- Take steroid medications like prednisone
- Take other anti-inflammatory pain relievers like ibuprofen or naproxen
- Drink three or more alcoholic beverages a day
If any of those apply, the 8-tablet maximum isn’t necessarily safe for you. The listed maximum is for otherwise healthy adults with no additional risk factors.
Why Children and Teens Should Avoid It
Alka-Seltzer Original is not appropriate for children or teenagers, especially those recovering from the flu, chickenpox, or other viral illnesses. The aspirin in each tablet has been linked to Reye’s syndrome, a rare but serious condition that causes swelling in the liver and brain. The Mayo Clinic specifically names Alka-Seltzer as one of the products parents might not realize contains aspirin. For fever or pain in kids and teens, acetaminophen or ibuprofen are safer alternatives.
Keeping Use Short-Term
Alka-Seltzer is designed for occasional use. If you find yourself reaching for it daily, that’s a signal something else is going on. Frequent heartburn, recurring headaches, or persistent stomach discomfort all have better long-term management options than repeated doses of an aspirin-based effervescent. Using aspirin-containing products regularly also increases the cumulative risk of stomach irritation and bleeding over time, even if each individual dose falls within the labeled limits.