Sucralfate: what it treats, how to take it, side effects
Last updated September 3, 2026.
Sucralfate is a protectant - it sticks to the raw ulcer tissue and forms a physical bandage against acid and enzymes so healing can happen underneath. You may know it as Carafate. It does not reduce acid; it covers the wound.
What does it treat?
Duodenal ulcers - sores in the first part of the small intestine - both treating active ones and preventing their return after they heal. If the ulcer traces to H. pylori, antibiotics handle the bacteria while sucralfate handles the wound.
How do you take it?
Four times a day for an active ulcer, twice a day for prevention - on an empty stomach, 1 hour before or 2 hours after meals, same times daily. Shake the liquid well before each dose. The schedule is demanding and it is the whole point: the coating lasts hours, so the day needs full coverage. Healing takes up to 8 weeks, and the medicine only works taken regularly - do not stop because the pain faded. Antacids, if prescribed, go at least 30 minutes apart from it. Missed dose: take it when you remember unless the next one is close; never double up.
Side effects to know
- Common: constipation - essentially the only common one, because the drug works locally and barely absorbs.
- Serious - call your doctor immediately or get emergency care: allergic signs - hives, rash, itching, difficulty breathing or swallowing, and swelling of the face, throat, tongue, or lips.
Who should not take it?
Anyone with a past allergic reaction to it. Flag kidney disease - the aluminum in sucralfate can accumulate when kidneys slow - and swallowing problems. It can bind other medications in the gut and block their absorption, so other drugs get spaced around it; your prescriber maps the schedule. If you become pregnant, call your doctor.
When is it an emergency?
Trouble breathing or swallowing, or swelling of the face, throat, or tongue is emergency care. For an overdose, call Poison Control at 1-800-222-1222. Pymander's escalation routing is built and tested specifically for this class of decision; see the safety architecture working paper.
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Common questions
Why four times a day on an empty stomach?
The drug is a physical coating - it needs an empty stomach to stick directly to the ulcer tissue instead of to your lunch, and the coating lasts only hours, so the day needs re-covering. MedlinePlus: 1 hour before or 2 hours after meals, four times daily for active ulcers. The schedule is annoying and it is also the entire mechanism.
Why do I keep taking it when the pain is gone?
Pain fades weeks before the ulcer actually closes - healing takes up to 8 weeks. Stopping early leaves a half-healed wound that reopens, and the ulcer returns with the habit. MedlinePlus says it directly: this medicine must be taken regularly to be effective. Finish the course, then let the follow-up confirm the healing.
Why did the pharmacist space my other pills around sucralfate?
Sucralfate binds things in the gut - that is how it coats the ulcer - and it will bind other medications too, carrying them out unabsorbed. The rule is spacing: other medications go at least a couple of hours apart, per your prescriber's schedule. Antacids specifically go at least 30 minutes away from it. This is the drug's one big logistical rule after the empty-stomach one.
Why did my doctor ask about my kidneys?
Sucralfate contains aluminum, and barely-absorbed does not mean never-absorbed - with healthy kidneys the small absorbed amount clears easily, but with kidney disease it can accumulate. That is why kidney disease is a before-you-start flag. For most people it is a non-issue; for slow kidneys, the prescriber weighs it.
How is sucralfate different from a PPI?
Opposite strategies. A PPI turns down acid production at the stomach's pumps - a whole-body chemistry change with a long-term ledger. Sucralfate changes no chemistry at all: it is a topical bandage for the ulcer, working locally and barely entering the bloodstream, which is why its common-effects list is essentially just constipation. Many ulcer plans use both: the PPI lowers the acid, the sucralfate covers the wound.
What happens if I miss a dose of sucralfate?
Take it as soon as you remember, unless it is almost time for the next one - then skip it and never double up. Because the drug is a coating, one missed dose just means an uncovered window - get back on schedule rather than stacking doses.