Trulance Side Effects: What to Expect and When to Call Your Doctor

Like all medications, Trulance (plecanatide) can cause side effects. Most are mild and manageable. But there are important warnings to know about — including a boxed warning from the FDA. This guide covers everything you need to know about Trulance side effects in plain language, including what to expect, what's normal, and when to call your doctor.

Trulance's Boxed Warning: Pediatric Risk

The FDA requires Trulance to carry its most serious type of warning — a boxed warning — due to risk of serious dehydration in pediatric patients:

Do not give Trulance to children under 6 years of age. In young juvenile animal studies, a single oral dose of plecanatide caused death due to severe dehydration. Children under 6 have higher intestinal expression of the GC-C receptor, making them much more susceptible to severe diarrhea and dehydration.

Trulance should be avoided in patients aged 6–17. Safety and effectiveness have not been established in this age group. The FDA labeling states to avoid use in patients 6 to less than 18 years of age.

Trulance is approved only for adults 18 and older.

Most Common Side Effect: Diarrhea

Diarrhea is the most common side effect of Trulance. In clinical trials:

• 5% of CIC patients taking Trulance reported diarrhea vs. 1% of placebo patients
• 4.3% of IBS-C patients taking Trulance reported diarrhea vs. 1% of placebo patients
• Severe diarrhea occurred in 0.6% of CIC patients and 1% of IBS-C patients

Importantly, Trulance is associated with lower rates of diarrhea than its main competitor Linzess (linaclotide), which is one reason some patients and doctors prefer it. Diarrhea most often appears within the first 4 weeks of treatment.

If diarrhea is mild, it often resolves as your body adjusts. If it becomes severe, stop taking Trulance and contact your doctor immediately. Drink plenty of fluids to prevent dehydration.

Other Common Side Effects

Beyond diarrhea, side effects reported by 1–2% of patients (but more than placebo) include:

• Nausea
• Abdominal distension (bloating)
• Flatulence (gas)
• Abdominal tenderness
• Nasopharyngitis (common cold symptoms)
• Upper respiratory tract infection
• Urinary tract infection
• Dizziness

Serious Side Effects: When to Call Your Doctor

While uncommon, these serious side effects require prompt medical attention:

• Severe diarrhea. If you develop severe diarrhea (very frequent, watery stools), stop Trulance immediately and contact your doctor. Severe diarrhea can cause dangerous dehydration and electrolyte imbalances. In clinical studies, 0.6–1% of patients experienced severe diarrhea; in some cases it appeared on the first day.
• Signs of dehydration. Extreme thirst, dry mouth, reduced urination, dizziness, or rapid heartbeat after taking Trulance warrant immediate medical evaluation.
• Elevated liver enzymes. A small number of patients in clinical trials had increased ALT and AST levels. Your doctor may order periodic liver function tests if you're on Trulance long-term.
• Allergic reaction. Though rare, signs of a serious allergic reaction (rash, hives, difficulty breathing, swelling of face or throat) require emergency medical care. Call 911 immediately.

Does Trulance Cause Weight Changes?

Clinical studies did not identify weight gain or weight loss as side effects of Trulance. It is not associated with body weight changes. If you notice unexplained weight changes while taking Trulance, discuss with your provider, as this may be related to a different cause.

Trulance and Pregnancy or Breastfeeding

There is limited data on Trulance use during pregnancy. Because plecanatide is negligibly absorbed systemically after oral administration, fetal exposure is expected to be minimal. However, insufficient human data exists to fully assess risks. Tell your doctor if you are pregnant, planning to become pregnant, or breastfeeding before starting Trulance.

Tips for Minimizing Side Effects

• Start drinking extra water when you begin Trulance — more fluids help moderate the GI effects
• Take it at the same time each day to maintain consistent levels
• Report any diarrhea that is severe or persists beyond 4 weeks to your provider
• Keep Trulance out of reach of children — this medication is dangerous for young children

The Bottom Line

Trulance is generally well tolerated. Diarrhea is the main side effect to watch for, and it's less frequent than with Linzess. Most patients who develop mild diarrhea find it resolves with time. Serious side effects are uncommon but warrant stopping the medication and calling your doctor immediately. For information on drug interactions, see our guide to Trulance drug interactions. And if you're having trouble finding Trulance at your pharmacy, medfinder can help.