What Is Mesalamine XR? Uses, Dosage, and What You Need to Know in 2026

Mesalamine XR is the extended-release formulation of mesalamine — a prescription medication used primarily to treat ulcerative colitis (UC), a chronic inflammatory disease of the large intestine. If you've recently been prescribed Mesalamine XR, or if you're trying to understand your medication better, this guide covers everything you need to know.

What Is Mesalamine XR?

Mesalamine XR (extended-release) is an oral capsule formulation of mesalamine, also known as 5-aminosalicylic acid (5-ASA). It's an aminosalicylate — a class of anti-inflammatory drugs used specifically for inflammatory bowel disease (IBD). Unlike immediate-release formulations, the XR designation means the drug is slowly released throughout the GI tract, delivering the medication where it's needed most: the colon and intestinal lining.

Mesalamine was first approved by the FDA in December 1987. The extended-release capsule formulation (Pentasa) has been available since the early 1990s, and generic versions entered the market in 2022. Brand names for the XR capsule formulation include:

Pentasa: 250 mg and 500 mg extended-release capsules (Takeda Pharmaceuticals)

Apriso: 0.375 g (375 mg) extended-release capsules (Salix Pharmaceuticals/Bausch Health)

Generic mesalamine ER: Available from multiple manufacturers in 0.375 g and 500 mg strengths

What Is Mesalamine XR Used For?

Mesalamine XR has two primary FDA-approved indications:

Treatment of mild to moderately active ulcerative colitis (induction of remission): reducing inflammation and symptoms during active flares.

Maintenance of remission of ulcerative colitis: preventing flares in patients who have already achieved remission.

Ulcerative colitis affects approximately 600,000–900,000 Americans. It causes inflammation and sores (ulcers) in the lining of the large intestine and rectum, producing symptoms like bloody diarrhea, abdominal cramping, urgency, and fatigue. Mesalamine is often the first-line treatment for mild-to-moderate disease.

Off-label, clinicians sometimes prescribe mesalamine for Crohn's disease following bowel surgery, though evidence for this use is less robust than for UC.

Dosage: How Much Mesalamine XR Should You Take?

Dosing depends on which formulation you're taking and your treatment goal:

Mesalamine ER 500 mg (Pentasa/generic): 1 g (two 500 mg capsules) four times daily = 4 g/day total for treatment of active UC. This is a multi-dose regimen.

Mesalamine ER 0.375 g (Apriso/generic): 1.5 g (four 0.375 g capsules) once daily in the morning for maintenance of remission. Approved for adults only.

Research has shown that 80% of patients on daily oral doses of 4–6 grams of mesalamine achieve complete or significant clinical improvement within 4 weeks, though full remission may take up to 6 weeks.

How to Take Mesalamine XR Correctly

Swallow capsules whole: Do not crush, chew, or break them — this destroys the extended-release mechanism.

Can be sprinkled (Pentasa only): If you can't swallow capsules, the Pentasa/generic 500 mg capsule contents can be sprinkled on a tablespoon of applesauce or yogurt and swallowed immediately without chewing.

Timing: Mesalamine ER can be taken with or without food. Apriso (0.375 g) should be taken in the morning. Follow your prescriber's specific instructions.

Drink water: Stay well hydrated while taking mesalamine to support kidney health.

Missed dose: Take the missed dose as soon as you remember, unless it's almost time for your next dose. Never double up.

Who Should Not Take Mesalamine XR?

Known allergy to mesalamine, other aminosalicylates, or salicylates (including aspirin)

Severe kidney or liver disease

Urinary tract obstruction

Phenylketonuria (PKU): Apriso brand capsules contain aspartame that forms phenylalanine

Is Mesalamine XR a Controlled Substance?

No. Mesalamine XR is not a controlled substance and is not scheduled under the DEA. It does not have abuse potential, and prescriptions can be written by any licensed provider including NPs and PAs. This also means it can be prescribed via telehealth without restrictions.

Finding Mesalamine XR in Stock in 2026

Due to an active ASHP back order on Sun Pharma's 500 mg ER capsules in 2026, finding Mesalamine XR at your pharmacy can require extra effort. medfinder can help you locate which pharmacies near you currently have your medication in stock.

For the latest on supply availability, see: Mesalamine XR shortage update: what patients need to know in 2026.