Linaclotide (Linzess)
Linaclotide (synthetic 14-amino-acid guanylate cyclase-C agonist peptide)
Approved status applies to specific products, routes, and indications, not every use context discussed online.
An FDA-approved daily capsule (Linzess) that relieves constipation and belly pain in people with irritable bowel syndrome with constipation (IBS-C) and chronic constipation. It works by increasing fluid in the intestines and reducing pain signals in the gut. Also approved for children age 6 and older.
Safety Summary
Diarrhea is the dominant tolerability issue across all clinical trials and real-world data. In the pivotal Phase 3 IBS-C trial (PMID 22986440), diarrhea occurred in 19.5% of linaclotide-treated patients vs 3.5% placebo, with severe diarrhea in 2% and discontinuation due to diarrhea in 5.7%. In pooled IBS-C trials (FDA label Table 1), diarrhea was reported in 20% vs 3%. In the Phase 3b adult CIC bloating trial, diarrhea rates were 5.9% with 145 mcg and 16.9% with 290 mcg vs 2.3% with placebo, with no serious diarrhea-related AEs (PMID 26222318). In the large Chinese real-world study (N=2963), diarrhea was reported in 10.0%, all mild or moderate, with 1.8% discontinuing due to diarrhea (PMID 39917729). In pediatric FC trials, diarrhea occurred in 4% with 72 mcg vs 2% placebo; in pediatric IBS-C, 7% with 145 mcg (FDA label 2025). The current FDA label warns that severe diarrhea can occur and instructs suspension plus rehydration if it does. URTI (5% vs 4%) and sinusitis (3% vs 2%) were reported at ≥2% incidence in CIC trials (FDA label Table 2). A pharmacovigilance study identified a signal for muscle spasms associated with linaclotide (ROR 1.88, 95% CI 1.63-2.18), predominantly in females and early in treatment (PMID 40843382). Overall only 2.4% of patients in the real-world study discontinued due to any adverse event (PMID 39917729).
Clinical check-in
If real-world use or exposure is being considered, review potential interactions, contraindications, and monitoring needs with a licensed clinician rather than relying on summary copy alone.
Sources: [1-13]