How long does Aluminum Hydroxide stay in your system?
Last updated September 7, 2026.
Aluminum hydroxide neutralizes stomach acid for about 20 to 60 minutes on an empty stomach and up to about 3 hours when you take it after a meal, and most of the dose leaves your body in stool within 1 to 3 days. How long the relief lasts depends mostly on whether you take it with food, since food keeps the antacid in your stomach longer. Only a small fraction of the aluminum is absorbed into your blood, and healthy kidneys filter it out in urine over the following days. Timing around other medicines matters more than the drug clearing your system, because aluminum hydroxide binds drugs such as tetracycline antibiotics, levothyroxine, and iron, so separate those doses by at least 2 hours. Constipation is a common sign the aluminum is still moving through your gut, and fluids plus regular activity help. If you need an antacid most days for more than 2 weeks, talk with a clinician instead of continuing on your own.
What to do
- Take it after meals: Dosing about 1 hour after eating stretches the acid-neutralizing effect closer to 3 hours.
- Space other medicines: Leave at least 2 hours between aluminum hydroxide and antibiotics, thyroid medicine, or iron so they still absorb properly.
- Watch your bowels: Drink water and stay active, and stop and ask about a different antacid if constipation sets in.
- Flag kidney problems: Tell a clinician before regular use if you have chronic kidney disease or are on dialysis, since aluminum can accumulate.
- Cap the duration: Antacids are meant for short-term relief, so get symptoms lasting more than 2 weeks checked.
- Get urgent care: Seek care now for trouble swallowing, vomiting blood, black stools, unexplained weight loss, or chest pain.
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