Trofinetide (Daybue and Daybue Stix): uses, availability and side effects

[admin]

Generic medicine: TrofinetideBrand names: Daybue and Daybue Stix
Availability and regulatory approval differ between countries.

What is Daybue?
Trofinetide is a prescription medicine developed to treat Rett syndrome symptoms. It is not an epilepsy medicine and it is not a cure for Rett syndrome. Exactly how it works is not fully understood.

In the United States, the FDA has approved Daybue for adults and children aged 2 years and older with Rett syndrome. Daybue is supplied as a prepared oral solution. Daybue Stix is a powder that must be mixed into an oral solution. Both can be administered by mouth or through a gastrostomy tube as directed.

The dose is based on body weight and is normally given twice daily. Always follow the prescribed product’s preparation, measurement, storage and administration instructions.

Availability outside the United States
Approval and access are not the same worldwide. In February 2026, the European Medicines Agency’s medicines committee recommended refusing an EU marketing authorisation for Daybu. Families should check the current position with their national regulator and Rett specialist rather than assuming it is locally approved or funded.

Most common side effects
• Diarrhoea, which can sometimes be severe
• Vomiting

Other reported side effects
• Weight loss
• Reduced appetite
• Tiredness
• Fever
• Anxiety
• Seizures
• Cold-like symptoms

Important risks and monitoring
Diarrhoea and dehydration: Diarrhoea was very common in the clinical study. The prescriber may recommend changes to laxatives, fluids, feeding or antidiarrhoeal treatment. Do not make these changes without an agreed plan.

Vomiting and aspiration: Vomit can enter the lungs and cause aspiration pneumonia, a particular concern when swallowing or airway protection is impaired. Tell the clinical team if vomiting is severe or frequent. Follow the product instructions about what to do after a vomited dose; do not automatically repeat it.

Weight and nutrition: Weight should be monitored. The prescriber may interrupt treatment, reduce the dose or stop treatment if significant weight loss occurs.

Kidney health and interactions: Tell the prescriber about kidney problems and provide a full list of medicines, supplements, laxatives and feeding products.

Seek urgent medical advice for
Signs of dehydration such as very little urine, unusual sleepiness or marked weakness; persistent or severe vomiting; breathing difficulty, coughing or fever after vomiting; inability to tolerate feeds or fluids; or a significant increase in seizures.

What the main trial found
FDA approval was supported by a 12-week randomised placebo-controlled trial in 187 participants. The study found statistically significant differences on caregiver and clinician measures, but response varies and not everyone benefits. Families and clinicians should weigh possible benefit against side effects and treatment burden.

FDA overview: https://www.fda.gov/drugs/news-events-h ... t-syndrome
Current US prescribing information: https://dailymed.nlm.nih.gov/dailymed/d ... 6c6a4b8257
FDA trial summary: https://www.fda.gov/drugs/drug-trials-s ... ots-daybue
EMA decision: https://www.ema.europa.eu/en/news/meeti ... ruary-2026

Information checked 4 September 2026. This is general information, not prescribing advice. Do not start, stop or change Daybue, bowel medicines or other treatment without the prescribing team.