What diseases does mesalamine treat?

October 11, 2025 •

3 min read

Over one million Americans live with Inflammatory Bowel Disease (IBD), and for many, mesalamine is a critical component of their treatment plan. This medication is most notably prescribed for managing a specific form of IBD, addressing chronic inflammation in the digestive tract.

Quick Summary

Mesalamine is an anti-inflammatory drug primarily used to treat and maintain remission in mild-to-moderate ulcerative colitis. It can be administered orally or rectally. The medication is also explored for other inflammatory bowel conditions, though its efficacy can vary.

Key Points

Primary use is ulcerative colitis: Mesalamine is a first-line treatment for mild-to-moderate ulcerative colitis, both for inducing and maintaining remission.
Limited role in Crohn's disease: Although sometimes used off-label, guidelines generally do not recommend mesalamine for treating active Crohn's disease due to controversial evidence of effectiveness.
Multiple formulations for targeted delivery: The medication is available as oral tablets, capsules, and rectal enemas or suppositories to treat different affected areas of the colon and rectum.
Anti-inflammatory mechanism: Mesalamine works by reducing inflammation directly in the intestinal lining to relieve symptoms like abdominal pain and bloody diarrhea.
Used for some pouchitis cases: Mesalamine enemas may be used for pouchitis, but its use is not recommended for chronic antibiotic-refractory cases based on recent guidelines.
Investigational for diverticulitis: Some studies have explored mesalamine for diverticulitis, but its role in treatment is not yet firmly established.
Associated with rare but serious side effects: While generally well-tolerated, mesalamine has a small risk of serious side effects, including kidney problems and hypersensitivity reactions.

Primary Indication: Ulcerative Colitis

Mesalamine, also known as 5-aminosalicylic acid (5-ASA), is an aminosalicylate medication with anti-inflammatory properties. Its primary and most established use is for the treatment of ulcerative colitis (UC). UC is a chronic inflammatory bowel disease that causes long-lasting inflammation and ulcers (sores) in the lining of the colon and rectum. Mesalamine is a cornerstone of therapy for many individuals with mild to moderate UC.

How Mesalamine Works for UC

The precise mechanism of action for mesalamine is not fully understood, but it is believed to work topically, directly on the surface of the bowel lining. The medication is designed to be released in the intestines, where it inhibits the production of inflammatory chemicals, such as prostaglandins and leukotrienes. By reducing this inflammation, mesalamine helps to alleviate the symptoms of UC, including:

Diarrhea
Rectal bleeding
Abdominal pain and cramping

Formulations for UC Treatment

The most effective route of administration for mesalamine depends on the location and extent of the inflammation in the colon. Different formulations are available to ensure the medication reaches the affected area directly.

Oral formulations: Capsules and tablets (such as Apriso, Asacol HD, Delzicol, and Lialda) are designed with special coatings to ensure the medication is released into specific parts of the small or large intestine.
Rectal formulations: Enemas (such as Rowasa) are ideal for treating inflammation in the rectum and lower colon (proctitis or proctosigmoiditis). Suppositories (such as Canasa) target inflammation confined to the rectum.

Off-Label and Investigational Uses

While UC is the main approved indication, mesalamine is sometimes used for other inflammatory conditions, though with varying levels of evidence supporting its efficacy.

Crohn's Disease

Mesalamine is occasionally prescribed off-label to treat mild-to-moderate Crohn's disease (CD), another form of IBD. However, its effectiveness for CD is a subject of debate in the medical community. Many studies have not consistently shown a significant benefit, and major gastroenterology guidelines do not recommend mesalamine for treating active Crohn's disease in adults. It is essential for patients with Crohn's to discuss the pros and cons of using mesalamine with their healthcare provider.

Pouchitis

Pouchitis is an inflammation of the internal pouch created during certain surgical procedures for UC. Mesalamine enemas have been explored as a potential treatment for pouchitis. However, recent American Gastroenterological Association guidelines suggest against using mesalamine for the treatment of chronic antibiotic-refractory pouchitis.

Diverticulitis

Diverticulitis involves inflammation or infection of small pouches (diverticula) that can form in the digestive tract. Some studies have investigated the use of mesalamine to reduce inflammation during an acute diverticulitis flare-up and for prevention. While some early research suggested potential benefits, further studies are needed to establish mesalamine's role in the routine management of diverticulitis.

Comparison of Mesalamine Formulations

Choosing the right mesalamine formulation depends on the disease's location and severity. The table below compares the typical use cases for different mesalamine delivery methods.


Formulation	Target Area	Primary Use	Administration	Key Considerations
Oral Tablets/Capsules	Colon and Small Intestine	Treating mild-to-moderate UC and maintaining remission	Taken by mouth, usually once or multiple times daily	Systemic delivery, dosage varies by brand
Rectal Enemas	Rectum and Left Colon	Treating distal UC (proctosigmoiditis)	Inserted rectally, typically at bedtime	Concentrated, local delivery; can cause discomfort
Rectal Suppositories	Rectum	Treating UC confined to the rectum (proctitis)	Inserted rectally	Local action with minimal systemic absorption

Conclusion

Mesalamine is a highly effective medication for inducing and maintaining remission in patients with mild to moderate ulcerative colitis. Its anti-inflammatory action targets the inflamed lining of the colon and rectum, reducing symptoms and preventing flare-ups. While primarily indicated for UC, its potential use for other conditions like Crohn's disease, pouchitis, and diverticulitis is more limited or still under investigation, with medical guidelines often advising against its routine use for active Crohn's. A healthcare provider can determine the most appropriate mesalamine formulation and treatment plan based on the specific condition and individual patient needs.

For more detailed information on inflammatory bowel disease, the Crohn's & Colitis Foundation is an authoritative resource.

Frequently Asked Questions

Mesalamine is primarily used to treat and prevent flare-ups of mild to moderately active ulcerative colitis, an inflammatory bowel disease.

No, mesalamine does not cure ulcerative colitis. It helps manage the condition by treating active inflammation and maintaining remission, but UC is a chronic disease requiring ongoing management.

Mesalamine is sometimes used for Crohn's disease, but its efficacy is not as well-established as for ulcerative colitis. Many guidelines do not recommend it for active Crohn's.

Mesalamine is an anti-inflammatory agent that works locally in the intestines to reduce inflammation. It is believed to inhibit inflammatory chemicals in the bowel lining.

Common side effects include headache, nausea, diarrhea, abdominal pain, and heartburn. Serious side effects are rare.

Mesalamine is available in oral forms (delayed-release tablets and capsules) and rectal forms (enemas and suppositories).

Mesalamine intolerance syndrome is a rare but serious adverse reaction that can mimic a flare-up of inflammatory bowel disease, with symptoms like increased cramping, bloody diarrhea, fever, headache, and rash.