How to take Alka-Seltzer Plus tablets
Alka-Seltzer Plus tablets dissolve in water to create a fizzy drink that you swallow. Drop the tablets into a glass of cold or warm water, wait for them to stop fizzing (usually 30 seconds to a minute), then drink the entire mixture right away. Do not swallow the tablets whole or chew them — they are designed to dissolve first.
The standard dose for adults and children 12 and older is two tablets per dose. You can repeat this dose every four to six hours, but do not take more than eight tablets in 24 hours. If you are under 12, check the package label or talk to a pharmacist before use, as dosing differs by product type and age.
Take Alka-Seltzer Plus with food or milk if it upsets your stomach. The medication works best when you take it at the first sign of symptoms, rather than waiting until symptoms are severe. Keep track of when you last took a dose so you do not accidentally take it too soon.
Key Takeaways
- Dissolve two tablets in a glass of water and drink the entire mixture — do not swallow the tablets whole.
- You can take a dose every four to six hours, but do not exceed eight tablets in a 24-hour period.
- Alka-Seltzer Plus contains multiple active ingredients, so read the label to confirm which symptoms it treats and check for any ingredients you should avoid.
- Do not use Alka-Seltzer Plus if you are allergic to aspirin, have stomach ulcers, take blood thinners, or are pregnant without talking to a doctor first.
- Common side effects include heartburn, nausea, or stomach upset; stop use and contact a doctor if you experience severe symptoms or signs of an allergic reaction.
What active ingredients are in Alka-Seltzer Plus
Alka-Seltzer Plus tablets contain three main active ingredients: aspirin (a pain reliever and fever reducer), phenylephrine (a decongestant), and chlorpheniramine (an antihistamine). Different formulations of Alka-Seltzer Plus may swap out one or more of these ingredients — for example, some versions include dextromethorphan (a cough suppressant) instead of or in addition to the antihistamine.
Before you use any Alka-Seltzer Plus product, read the label carefully to see exactly which ingredients are in that specific version. This matters because you may already be taking another medication that contains one of these ingredients, and doubling up can be unsafe. For instance, if you are already taking a separate decongestant or pain reliever, adding Alka-Seltzer Plus could push you over the safe daily limit.
Who should not use Alka-Seltzer Plus
Do not use Alka-Seltzer Plus if you are allergic to aspirin or any other ingredient in the product. If you have a history of stomach ulcers, bleeding problems, or severe heartburn, talk to a doctor or pharmacist before use. Aspirin can irritate the stomach lining and increase bleeding risk in people with these conditions.
If you take blood thinners (such as warfarin or clopidogrel), have high blood pressure, or are pregnant or breastfeeding, do not use Alka-Seltzer Plus without checking with a doctor first. Aspirin during pregnancy, especially in the third trimester, can cause complications. The decongestant phenylephrine can also raise blood pressure and may not be safe for people with certain heart or blood pressure conditions.
Children under 12 should not use Alka-Seltzer Plus without a doctor's recommendation. Some formulations are not intended for young children, and dosing depends on the child's age and weight.
Common side effects and when to stop
Mild side effects from Alka-Seltzer Plus may include heartburn, nausea, stomach upset, or dizziness. These effects often fade as your body adjusts. If you experience mild side effects, try taking the medication with food or milk, or reduce the dose.
Stop using Alka-Seltzer Plus and contact a doctor or poison control if you notice severe stomach pain, vomiting blood, black or tarry stools, difficulty breathing, chest pain, severe dizziness, or signs of an allergic reaction (rash, swelling of the face or throat, difficulty swallowing). These can signal a serious problem that needs medical attention.
How Alka-Seltzer Plus differs from regular Alka-Seltzer
Regular Alka-Seltzer contains only aspirin and an antacid (sodium bicarbonate) and is designed to relieve heartburn and indigestion. Alka-Seltzer Plus adds a decongestant and often an antihistamine or cough suppressant, making it intended for cold and flu symptoms like congestion, cough, and body aches — not just stomach upset.
If you have a cold with congestion and body aches, Alka-Seltzer Plus is the right choice. If you have only heartburn or indigestion, regular Alka-Seltzer is simpler and contains fewer ingredients. Check the label on the box to confirm which product you are holding, since the packaging can look similar.
Storage and safety tips
Store Alka-Seltzer Plus tablets in a cool, dry place away from moisture and heat. Keep the container tightly closed. Do not store tablets in the bathroom, where humidity from showers can cause them to break down faster. Check the expiration date on the package before use — expired tablets may not work as intended.
Keep Alka-Seltzer Plus out of reach of children and pets. If someone swallows more than the recommended dose, contact poison control when ready at 1-800-222-1222 (in the United States) or your local emergency number. Have the product label or box available when you call so you can tell them exactly what was taken.
Drug interactions to watch for
Alka-Seltzer Plus can interact with several common medications. If you take blood thinners, certain blood pressure drugs, or other pain relievers, the aspirin in Alka-Seltzer Plus may increase your risk of bleeding or other side effects. Combining it with other decongestants or antihistamines can also cause problems.
Before using Alka-Seltzer Plus, make a list of all medications and supplements you take — including over-the-counter products — and show it to a pharmacist. They can tell you whether it is safe to combine Alka-Seltzer Plus with what you are already taking. This step takes only a few minutes and can prevent a serious interaction.
Frequently Asked Questions
Can I take Alka-Seltzer Plus with other cold medicines?
No, not without checking first. Many cold and flu products contain overlapping ingredients like decongestants, pain relievers, or antihistamines. Taking Alka-Seltzer Plus alongside another cold medicine could cause you to exceed safe daily limits for one or more ingredients. Read all labels and ask a pharmacist before combining products.
How long does it take for Alka-Seltzer Plus to work?
Most people notice relief within 15 to 30 minutes of drinking the dissolved tablets. The fizzy formulation allows the active ingredients to enter your bloodstream faster than a solid tablet would. If you do not feel better after an hour, do not take another dose before the four-hour mark.
Is Alka-Seltzer Plus safe during pregnancy?
Aspirin during pregnancy, especially in the third trimester, can cause complications for both mother and baby. If you are pregnant or think you might be, do not use Alka-Seltzer Plus without talking to your doctor or midwife first. They can recommend safer alternatives for your symptoms.
Can I take Alka-Seltzer Plus on an empty stomach?
You can, but it may cause stomach upset or heartburn. Taking it with food or milk can reduce this risk. If you have a history of stomach ulcers or severe heartburn, avoid taking it on an empty stomach and talk to a doctor before use.
What should I do if I accidentally take too much?
Contact poison control at 1-800-222-1222 (United States) or your local emergency number right away. Have the product box or label ready so you can tell them how many tablets were taken and when. Do not wait for symptoms to appear — call when ready.