What the label lists and what reports show
Mesalamine side effects
Mesalamine's FDA label: “Most common adverse reactions (≥3%) are: headache, diarrhea, upper abdominal pain, nausea, and nasopharyngitis.” FAERS holds 55,833 reports naming it through July 30, 2026; the reaction reported most often, leaving out the conditions it is used for, product-use terms and outcomes, is colitis ulcerative (6,709 reports).
- Generic listed
- A presentation discontinued
Check it at the source: the mesalamine FDA label on DailyMed (effective August 27, 2026, Salix Pharmaceuticals, Inc.); the FDA FAERS public dashboard.
What does the label list?
From the label: adverse reactionsMost common adverse reactions (≥3%) are: headache, diarrhea, upper abdominal pain, nausea, and nasopharyngitis.
Table 3: Adverse Reactions Reported in at least 1% of patients in Three Trials of Maintenance of Remission in Adults with Ulcerative Colitis
This table is printed in the Lialda label published by Takeda Pharmaceuticals America, Inc. of March 24, 2026; the label quoted above does not print one.
| Adverse Reaction | LIALDA 2.4 g/day Administered either as 1.2 g twice daily or 2.4 g once daily (n=1082) % |
|---|---|
| Headache | 3% |
| Liver function test abnormal | 2% |
| Abdominal pain | 2% |
| Diarrhea | 2% |
| Abdominal distension | 1% |
| Abdominal pain upper | 1% |
| Dyspepsia | 1% |
| Back pain | 1% |
| Rash | 1% |
| Arthralgia | 1% |
| Fatigue | 1% |
| Hypertension | 1% |
Rows and numbers as the label prints them, under its own column headings (the first rows of a longer table where it runs on). A reaction in a trial table is not necessarily caused by the medicine, and trials differ from everyday use.
From the label: adverse reactions, continuedThe following clinically significant adverse reactions are described elsewhere in labeling: Renal Impairment [see Warnings and Precautions ( 5.1 )] Mesalamine-Induced Acute Intolerance Syndrome [see Warnings and Precautions ( 5.2 )] Hypersensitivity Reactions [see Warnings and Precautions ( 5.3 )] Hepatic Failure [see Warnings and Precautions ( 5.4 )] Severe Cutaneous Adverse Reactions [see Warnings and Precautions (5.5) ] Photosensitivity [see Warnings and Precautions ( 5.6 )] Nephrolithiasis [see Warnings and Precautions ( 5.7 )] Risks in Patients with Phenylketonuria [see Warnings and Precautions ( 5.8 )] Most common adverse reactions (≥3%) are: headache, diarrhea, upper abdominal pain, nausea, and nasopharyngitis. ( 6.1 ) To report SUSPECTED ADVERSE REACTIONS, contact Salix Pharmaceuticals at 1-800-321-4576 or FDA at 1-800-FDA-1088 or www.fda.gov/medwatch. 6.1 Clinical Trials Experience Because clinical studies are conducted under widely varying conditions, adverse reaction rates observed in the clinical trials of a drug cannot be directly compared to rates in the clinical trials of another drug and may not reflect the rates observed in practice. The data described below reflect exposure to APRISO in 557 patients, including 354 exposed for at least 6 months and 250 exposed for greater than one year. …
Source: FDA drug label, Salix Pharmaceuticals, Inc., effective August 27, 2026 (SPL set 7951139c-b271-45a4-b523-34b23800917b), via openFDA; the full label on DailyMed
What do FAERS reports show?
55,833 reports list mesalamine among the medicines taken, each a report of something that happened, not proof the medicine caused it; 2,749 are coded as a death and 17,399 as a hospital stay. Counts follow how widely a medicine is used and watched, and they are not a measure of how risky it is. Of the 20 reactions below, 9 are named by the same term (in US spelling) in the label's adverse reactions, warnings or patient leaflet; a reaction the label does not name may still be there under another word, and a report does not show that the medicine caused it.
Reports received each year
The 25 most reported reactions
Source: FDA Adverse Event Reporting System (FAERS) via openFDA, reports through July 30, 2026; reactions as MedDRA preferred terms
What next?
- Mesalamine: the full record
- label, generics, price, shortages, recalls
- Report a side effect to the FDA
- MedWatch
- Side effects hub
- the most reported medicines and reactions