Aluminum Hydroxide: Heartburn Relief, Dosing, and Side Effects
Last updated September 7, 2026.
**Aluminum hydroxide is an antacid, a medicine that neutralizes acid already sitting in your stomach.** It reacts with stomach acid to raise the pH of the stomach contents, which eases burning within minutes and lets irritated tissue settle. It also binds phosphate in the gut, which is why doctors sometimes prescribe it for high phosphate levels in kidney disease. The main safety point is that it is meant for short bursts of use: if you need it more than 2 weeks in a row, or you have kidney disease, talk with a doctor instead of continuing on your own.
What does it treat?
Aluminum hydroxide treats heartburn, acid indigestion, sour stomach, and the upper belly burning that shows up after a large or fatty meal, after coffee or alcohol, or when you lie down soon after eating. It works on symptoms you already have rather than preventing them, so it fits occasional flares better than daily reflux. Doctors also use it under prescription to lower high blood phosphate in people with chronic kidney disease, where it binds phosphate from food in the intestine. You will often meet it inside combination products: with magnesium hydroxide (Maalox, Mylanta) to balance out constipation, with simethicone added for gas and bloating, and with magnesium carbonate in some Gaviscon products.
How do you take it?
The usual over-the-counter form is an oral suspension, commonly 600 mg per 5 mL, and there are chewable tablets and capsules. A typical adult dose is 5 to 10 mL (1 to 2 teaspoonfuls) between meals and at bedtime, or when symptoms hit. Do not take more than 8 doses in 24 hours, and do not use the maximum dose for more than 2 weeks unless a doctor tells you to. Shake the suspension well, and take it between meals rather than with food, since taking it on a full stomach mostly prolongs the effect rather than adding relief; for phosphate binding, the prescribed dose is taken with meals instead. It is taken as needed, so there is no missed dose to make up: take it when symptoms return and skip the one you forgot. Separate it from other medicines by at least 2 hours. Stop and call a doctor if you still need it after 2 weeks, if the burning comes back as soon as the dose wears off, or if you develop constipation you cannot clear, new belly pain, or vomiting.
Side effects to know
- Common: The most common effect is constipation, and you may notice a chalky taste or whitish, speckled stools, which is harmless.
- Serious: Stop taking it and get medical help for constipation that turns into no stool and no gas with a swollen, painful belly, for vomiting or vomit that looks like coffee grounds, or for black tarry stools. With long or heavy use, especially if your kidneys do not work well, aluminum and phosphate problems can build up and show as bone pain, muscle weakness, unusual tiredness, or confusion, all of which need prompt evaluation.
Who should not take it?
Talk with a doctor before using it if you have kidney disease or are on dialysis, since your body clears aluminum through the kidneys and it can accumulate; if you have low phosphate levels; if you are on a sodium-restricted diet, because some products carry meaningful sodium; or if you have ongoing constipation, a history of bowel obstruction, or an ostomy. It blocks absorption of many drugs, so separate it by at least 2 hours from levothyroxine, iron, digoxin, isoniazid, ketoconazole, and tetracycline antibiotics such as doxycycline, and by at least 2 to 4 hours from fluoroquinolones such as ciprofloxacin and levofloxacin. Do not take it with citrate products such as calcium citrate, potassium citrate, or effervescent citric acid tablets, because citrate sharply increases how much aluminum your body absorbs. Current over-the-counter labeling tells you to ask a health professional before use if you are pregnant or breastfeeding; occasional antacid use in pregnancy is common practice, but regular or high-dose use should be a doctor's decision. Alcohol does not react with aluminum hydroxide, but it irritates the stomach lining and loosens the valve at the top of the stomach, so drinking will keep bringing the symptoms back.
When is it an emergency?
Call 911 in the US for chest pressure or chest pain with sweating, shortness of breath, or pain spreading to the arm, neck, or jaw, since a heart attack can feel like severe heartburn; for collapse or trouble breathing; and for swelling of the face, lips, or tongue, hives, or throat tightness, which suggest a severe allergic reaction. Call Poison Control at 1-800-222-1222 right away for any overdose or for a child who swallows a large amount, and for signs of aluminum or phosphate trouble such as severe muscle weakness, bone pain, confusion, or unusual drowsiness. Go to an emergency department for vomiting blood or coffee-ground material, black tarry stools, a swollen rigid belly with no stool or gas, or severe belly pain that keeps getting worse. Trouble or pain with swallowing, vomiting that will not stop, or losing weight without trying needs same-day medical care rather than more antacid.
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Common questions
What is the most aluminum hydroxide I can take in a day?
For the standard over-the-counter suspension, adults take 5 to 10 mL between meals and at bedtime, and no more than 8 doses in 24 hours. Chewable tablets and capsules have their own limits printed in the Drug Facts panel, so read the box rather than converting from teaspoons. The other ceiling matters just as much: do not use the maximum daily dose for longer than 2 weeks unless a doctor is directing it. Needing the top of the range every day is the signal that something other than an antacid is the right treatment.
Can I drink alcohol while taking it?
There is no chemical interaction between alcohol and aluminum hydroxide, so a drink will not make the antacid unsafe. The problem is that alcohol increases stomach acid, irritates the stomach lining, and relaxes the muscle that keeps acid out of the esophagus. That means you will likely need more doses and get less relief on nights you drink. If your heartburn is mostly appearing after drinking, cutting back does more than adding antacid does.
Is aluminum hydroxide safe in pregnancy or while breastfeeding?
Current over-the-counter labeling directs you to ask a health professional before use if you are pregnant or breastfeeding. In practice, antacids are among the first options clinicians use for heartburn in pregnancy, which is very common in the third trimester, and only small amounts of aluminum are absorbed. What clinicians want to avoid is regular high-dose or long-term use, and they will also check that you are not taking it close to a prenatal iron supplement, since it blocks iron absorption. Bring it up at a visit so you get a plan rather than an open-ended habit.
Should I take it with food or on an empty stomach?
For heartburn, take it between meals and at bedtime, which is when acid is most likely to cause symptoms. Taking it with a meal makes it last longer in the stomach but does not add relief for a symptom you do not have yet. If you were prescribed aluminum hydroxide to lower blood phosphate, the rule flips: take it with meals, because it needs to be in the stomach at the same time as the phosphate in your food. In either case, shake the suspension well before measuring.
What are the signs of taking too much?
Short-term overuse usually shows up as constipation that becomes hard stools, then belly pain, bloating, and eventually no stool and no gas passing. Longer or heavy use, especially with reduced kidney function, can drive phosphate too low and aluminum too high, which look like muscle weakness, bone or joint pain, loss of appetite, unusual tiredness, or confusion. Call Poison Control at 1-800-222-1222 for a suspected overdose or if a child swallows a large amount, and call 911 for collapse or trouble breathing. Do not treat the constipation with more antacid.
Which of my other medicines does it interfere with?
Aluminum hydroxide binds many drugs in the gut and keeps them from being absorbed. Separate it by at least 2 hours from levothyroxine, iron, digoxin, isoniazid, ketoconazole, and tetracyclines such as doxycycline, and by 2 to 4 hours from fluoroquinolones such as ciprofloxacin and levofloxacin. Avoid taking it together with citrate products such as calcium citrate or effervescent citric acid tablets, because citrate greatly increases aluminum absorption. Bring your full medicine list, including supplements, when you ask about starting it.