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Asacol HD Side Effects

Generic name: mesalamine

Medically reviewed by Philip Thornton, DipPharm. Last updated on Dec 15, 2023.

Note: This document contains side effect information about mesalamine. Some dosage forms listed on this page may not apply to the brand name Asacol HD.

Applies to mesalamine: oral capsule delayed release, oral capsule extended release, oral tablet delayed release, oral tablet enteric coated. Other dosage forms:

Serious side effects of Asacol HD

Along with its needed effects, mesalamine (the active ingredient contained in Asacol HD) may cause some unwanted effects. Although not all of these side effects may occur, if they do occur they may need medical attention.

Check with your doctor immediately if any of the following side effects occur while taking mesalamine:

More common

Less common


Incidence not known

Other side effects of Asacol HD

Some side effects of mesalamine may occur that usually do not need medical attention. These side effects may go away during treatment as your body adjusts to the medicine. Also, your health care professional may be able to tell you about ways to prevent or reduce some of these side effects.

Check with your health care professional if any of the following side effects continue or are bothersome or if you have any questions about them:

More common

Less common

Incidence not known

For Healthcare Professionals

Applies to mesalamine: compounding powder, oral capsule extended release, oral delayed release capsule, oral delayed release tablet, rectal enema, rectal kit, rectal suppository.


The most common adverse events were headache, eructation, and aggravation of ulcerative colitis.[Ref]


Very common (10% or more): Eructation (up to 16%), ulcerative colitis aggravated (up to 15%)

Common (1% to 10%): Abdominal pain/cramps/discomfort, diarrhea, flatulence, nausea, gastroenteritis, gastrointestinal hemorrhage, rectal disorder, stool abnormalities (color or texture change), urinary frequency, dyspepsia, vomiting, bloating, rectal distension, pain on insertion of tip (enema formulation), hemorrhoids, rectal pain, colitis, constipation, abdominal distension

Uncommon (0.1% to 1%): Acute pancreatitis, melena (bloody diarrhea), rectal pain/soreness/burning, pancolitis, neonate diarrhea, anal discomfort, defecation urgency, colitis ulcer (proctitis ulcer), glossitis, rectal polyp, pancreatitis, application site irritation (rectal foam formulation), painful rectal tenesmus, rectal urgency

Rare (less than 0.1%): Increased amylase

Frequency not reported: Duodenal ulcer, dysphagia, esophageal ulcer, fecal incontinence, GI bleeding, mouth ulcer, oral candidiasis, rectal bleeding, rectal polyp, mild indigestion and cramping, bloody diarrhea, stomatitis, abdominal enlargement, lipase increase

Postmarketing reports: Frequent bowel movements, mucus stools, painful defecation, proctalgia, rectal discharge, stomach discomfort, gastritis, dry mouth, oral ulcers, perforated peptic ulcer, amylase increased[Ref]

Nervous system

Very common (10% or more): Headache (up to 24%)

Common (1% to 10%): Dizziness

Uncommon (0.1% to 1%): Paresthesia, peripheral neuropathy, somnolence, tremor,

Very rare (less than 0.01%): Vertigo

Frequency not reported: Neuropathy, mild disorientation

Postmarketing reports: Guillain-Barre syndrome, hypertonia, transverse myelitis, hyperesthesia, taste perversion, tinnitus[Ref]


Very common (10% or more): Pain (up to 14%)

Common (1% to 10%): Asthenia, fatigue, pyrexia, infection

Uncommon (0.1% to 1%): Ear pain, peripheral edema

Rare (less than 0.1%): Drug fever

Frequency not reported: Malaise, mesalamine-induced acute intolerance syndrome, plugged ears, adenovirus infection, aching, decreased body mass index,

Postmarketing reports: Medication residue, elevated alkaline phosphatase, elevated GGT, elevated LDH, ear congestion[Ref]


Very common (10% or more): Nasopharyngitis (up to 15%)

Common (1% to 10%): Upper respiratory tract infection, influenza like symptoms, rhinitis, cold/sore throat

Uncommon (0.1% to 1%): Allergic and fibrotic lung reactions, dyspnea, cough, bronchospasm, pleural effusion, alveolitis, pulmonary eosinophilia, lung infiltration, pneumonitis, pharyngolaryngeal pain

Very rare (less than 0.01%): Eosinophilic pneumonia

Frequency not reported: Hypersensitivity pneumonitis (including interstitial pneumonitis, allergic alveolitis, eosinophilic pneumonitis, stuffy head, interstitial pulmonary fibrosis, bronchiolitis obliterans, sinusitis

Postmarketing reports: Fibrosing alveolitis, asthma exacerbation, pleuritis, bronchitis[Ref]


Common (1% to 10%): Hypertension, vasodilation,

Uncommon (0.1% to 1%): Pericarditis, myocarditis, pericardial effusion, tachycardia, hypotension

Frequency not reported: Chest pain, T-wave abnormalities, Kawasaki-like syndrome[Ref]


Common (1% to 10%): Rash, alopecia, urticaria, pruritus, acne

Uncommon (0.1% to 1%): Lupus erythematosus syndrome, allergic exanthema, increased sweating, angioedema, Stevens-Johnson syndrome, face edema

Very rare (less than 0.01%): Reversible alopecia, bullous skin reactions including erythema multiforme

Frequency not reported: Dry skin, eczema, erythema nodosum, nail disorder, photosensitivity, lichen planus, ecchymosis

Postmarketing reports: Prurigo, erythema, psoriasis, pyoderma gangrenosum[Ref]


Common (1% to 10%): Back pain, arthralgia, leg/joint pain

Uncommon (0.1% to 1%): Myalgia, chills, myositis, arthritis

Frequency not reported: Leg cramps, lower back discomfort, muscle cramps, neck pain

Postmarketing reports: Joint disorder, rheumatoid arthritis[Ref]


Common (1% to 10%): Hepatic function abnormal, increased alanine aminotransferase

Uncommon (0.1% to 1%): Hepatitis, increased liver enzymes (transaminase activity), intrahepatic cholestasis, increased bilirubin

Very rare (less than 0.01%): Hepatotoxicity (including cirrhosis, hepatic failure), changes in liver function parameters

Frequency not reported: GGTP increase, SGOT increase, SGPT increase, sclerosing cholangitis, increased alkaline phosphatase

Postmarketing reports: Jaundice, cholestatic jaundice, liver necrosis, cholecystitis[Ref]


Common (1% to 10%): Anorexia

Frequency not reported: Thirst, edema

Postmarketing reports: Increased appetite, gout[Ref]


Common (1% to 10%): Vision abnormalities

Uncommon (0.1% to 1%): Conjunctivitis

Postmarketing reports: Blurred vision, eye pain[Ref]


Uncommon (0.1% to 1%): Acute or chronic interstitial nephritis, renal insufficiency, renal failure, nephrotoxicity

Very rare (less than 0.01%): Nephrotic syndrome, urine discoloration

Frequency not reported: Creatinine clearance decreased

Postmarketing reports: Minimal change nephropathy, elevated serum creatinine and BUN[Ref]


Uncommon (0.1% to 1%): Thrombocytopenia, aplastic anemia, hemolytic anemia, agranulocytosis, leukopenia, neutropenia, pancytopenia, platelet count decreased

Very rare (less than 0.01%): Eosinophilia (as part of an allergic reaction), anemia, bone marrow depression

Frequency not reported: Thrombocythemia

Postmarketing reports: Granulocytopenia, lymphadenopathy[Ref]


Uncommon (0.1% to 1%): Allergic reaction, anaphylactic reaction, drug reaction with eosinophilia and systemic symptoms (DRESS)

Frequency not reported: Anaphylactic shock, angioedema[Ref]


Uncommon (0.1% to 1%): Oligospermia (reversible), UTI/urinary burning

Frequency not reported: Albuminuria, amenorrhea, breast pain, hematuria, hypomenorrhea, menorrhagia, metrorrhagia, urinary frequency

Postmarketing reports: Dysuria, urinary urgency, epididymitis[Ref]


Uncommon (0.1% to 1%): Insomnia

Frequency not reported: Depression, anxiety, decreased libido

Postmarketing reports: Nervousness, confusion, emotional lability, confusion[Ref]

Frequently asked questions


1. (2022) "Product Information. Asacol (mesalamine)." Procter and Gamble Pharmaceuticals

2. (2022) "Product Information. Rowasa (mesalamine)." Solvay Pharmaceuticals Inc

3. "Product Information. Pentasa (mesalamine)." Hoechst Marion Roussel

4. "Product Information. Canasa (mesalamine)." Axcan Pharma US Inc

5. Cerner Multum, Inc. "UK Summary of Product Characteristics."

6. (2022) "Product Information. Lialda (mesalamine)." Shire US Inc

7. Cerner Multum, Inc. "Australian Product Information."

8. "Product Information. Apriso (mesalamine)." Salix Pharmaceuticals

9. (2022) "Product Information. Delzicol (mesalamine)." Warner Chilcott Laboratories

Further information

Always consult your healthcare provider to ensure the information displayed on this page applies to your personal circumstances.

Some side effects may not be reported. You may report them to the FDA.