Yes, Maalox is an over-the-counter antacid. You can buy it at pharmacies, grocery stores, and online retailers without a prescription. It’s approved for relief of heartburn, sour stomach, acid indigestion, and upset stomach associated with overeating or drinking.
What Maalox Contains
Each 5 mL teaspoon of Maalox liquid contains three active ingredients: 200 mg of aluminum hydroxide, 200 mg of magnesium hydroxide, and 20 mg of simethicone. The first two are antacids that neutralize stomach acid. Simethicone is an anti-gas agent that helps break up gas bubbles in your digestive tract, which is why Maalox is often marketed for both heartburn and bloating.
Maalox comes in liquid suspension, chewable tablets, and extra-strength chewable tablets. The liquid tends to work faster because it coats the stomach lining immediately, while tablets need to dissolve first.
How It Works
When aluminum hydroxide hits your stomach acid, it splits apart and releases molecules that bind to free acid, converting it into water and harmless salts. Magnesium hydroxide does essentially the same thing through a slightly different chemical pathway. Together, they raise the pH in your stomach so it’s less acidic, which is what makes the burning sensation ease up. Relief typically starts within minutes of taking a dose.
The combination of aluminum and magnesium isn’t random. Aluminum-based antacids tend to cause constipation, while magnesium-based ones tend to have a laxative effect. Pairing them together helps cancel out both side effects, leaving most people with normal digestion.
Dosage and Duration
For the standard liquid, adults can take 10 to 20 mL (two to four teaspoons) four times daily. The maximum is 80 mL in 24 hours. For chewable tablets, the typical dose is one to four tablets every three to four hours, with a maximum of 16 tablets per day. Extra-strength tablets have a lower cap of eight per day.
Timing matters. Taking Maalox 20 minutes to one hour after meals and again at bedtime gives the best coverage, since stomach acid production peaks during and after eating. OTC labeling requires a clear warning: do not use the maximum dosage for more than two weeks without a doctor’s guidance. Maalox is designed for short-term, occasional relief, not as a long-term solution for chronic acid problems.
Who Should Avoid Maalox
People with kidney disease need to be especially careful. Healthy kidneys easily clear excess magnesium and aluminum from the body, but when kidney function declines, these minerals can build up. Magnesium-containing antacids are a well-documented cause of dangerously high magnesium levels in people with chronic kidney disease, particularly older adults. If you have any degree of kidney impairment, talk to your doctor before reaching for Maalox or any similar antacid.
Drug Interactions to Watch For
Maalox can interfere with how your body absorbs several common medications. The aluminum and magnesium in it bind to other drugs in the stomach, preventing them from getting fully absorbed into your bloodstream. This effectively makes those medications weaker.
The most notable interactions include:
- Certain antibiotics: tetracyclines (like doxycycline), quinolone antibiotics (like ciprofloxacin), and some cephalosporins all absorb poorly when taken alongside antacids
- Digoxin: a heart medication that can lose effectiveness
- Iron supplements: aluminum and magnesium reduce iron absorption
The general rule is to separate Maalox from other medications by at least two hours. If you take any prescription drugs, check with a pharmacist before adding Maalox to your routine. The OTC label itself carries a drug interaction warning about this.
How Maalox Compares to Similar Products
Mylanta, the most common competitor, contains the same three active ingredients: aluminum hydroxide, magnesium hydroxide, and simethicone. The differences between the two come down to flavoring, concentration, and brand availability rather than any meaningful difference in how they work. If you can find one but not the other, they’re functionally interchangeable.
Maalox works differently from acid reducers like famotidine (Pepcid) or omeprazole (Prilosec). Those drugs reduce how much acid your stomach produces in the first place, which takes longer to kick in but lasts for hours. Maalox neutralizes acid that’s already there, so it works within minutes but wears off faster. For occasional heartburn after a heavy meal, Maalox is a reasonable first choice. For heartburn that keeps coming back day after day, an acid reducer is usually more appropriate.