What the label lists and what reports show
Crofelemer side effects
Crofelemer's FDA label: “Most common adverse reactions (≥ 3%) are upper respiratory tract infection, bronchitis, cough, flatulence and increased bilirubin.” FAERS holds 233 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 diarrhoea (26 reports).
- No generic listed
Check it at the source: the crofelemer FDA label on DailyMed (effective July 31, 2026, Napo Pharmaceuticals, Inc.); the FDA FAERS public dashboard.
What does the label list?
From the label: adverse reactionsMost common adverse reactions (≥ 3%) are upper respiratory tract infection, bronchitis, cough, flatulence and increased bilirubin.
Table 1: Common Adverse Reactions occurring in at least 2% of patients and at a higher incidence than placebo in HIV-Positive Patients in Three Placebo-Controlled Trials
| Adverse Reaction | MYTESI 125 mg Twice Daily N = 229 n (%) | Placebo N = 274 n (%) |
|---|---|---|
| Upper respiratory tract infection | 13 (6) | 4 (2) |
| Bronchitis | 9 (4) | 0 |
| Cough | 8 (4) | 3 (1) |
| Flatulence | 7 (3) | 3 (1) |
| Increased bilirubin | 7 (3) | 3 (1) |
| Nausea | 6 (3) | 4 (2) |
| Back pain | 6 (3) | 4 (2) |
| Arthralgia | 6 (3) | 0 |
| Urinary tract infection | 5 (2) | 2 (1) |
| Nasopharyngitis | 5 (2) | 2 (1) |
| Musculoskeletal pain | 5 (2) | 1 (<1) |
| Hemorrhoids | 5 (2) | 0 |
| Giardiasis | 5 (2) | 0 |
| Anxiety | 5 (2) | 1 (<1) |
| Increased alanine aminotransferase | 5 (2) | 3 (1) |
| Abdominal distension | 5 (2) | 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, continuedMost common adverse reactions (≥ 3%) are upper respiratory tract infection, bronchitis, cough, flatulence and increased bilirubin. ( 6.1 ) To report SUSPECTED ADVERSE REACTIONS, contact Napo Pharmaceuticals at 1-844-722-8256 or FDA at 1-800-FDA-1088 or www.fda.gov/medwatch. 6.1 Clinical Trials Experience Because clinical trials 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. A total of 696 HIV-positive patients in three placebo-controlled trials received MYTESI for a mean duration of 78 days. Of the total population across the three trials, 229 patients received a dosage of 125 mg twice a day for a mean duration of 141 days, and 171 patients received one of four higher than recommended dosages for a mean duration of 139 days (N=69) 14 days (N=102), 146 days (N=54), and 14 days (N=242), respectively. Adverse reactions in patients treated with MYTESI 125 mg twice daily that occurred in at least 2% of patients and at a higher incidence than placebo are provided in Table 1 .
Source: FDA drug label, Napo Pharmaceuticals, Inc., effective July 31, 2026 (SPL set 45584fba-8081-4cd1-a21e-3ea8237f62ff), via openFDA; the full label on DailyMed
What do FAERS reports show?
233 reports list crofelemer among the medicines taken, each a report of something that happened, not proof the medicine caused it; 29 are coded as a death and 29 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, 8 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.
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?
- Crofelemer: 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