Common Side Effects of Relyvrio
Relyvrio (sodium phenylbutyrate/taurursodiol) causes diarrhea, upper respiratory tract infection, nausea, constipation, muscle spasm, decreased appetite, fatigue, back pain, and abdominal distension. These occurred in at least 10% of patients in clinical trials.[1]
Serious Side Effects and Warnings
Serious risks include pancreatitis, which requires immediate discontinuation if suspected. It worsens ALS symptoms if taken after the expiration date due to potential breakdown into toxic impurities. Avoid in patients with severe liver disease, as it increases exposure to active components.[1][2]
Side Effects Patients Report Most
In real-world use and trials, gastrointestinal issues like diarrhea and nausea top complaints, often leading to dose adjustments. Some patients note fatigue and muscle spasms worsening ALS progression symptoms, though causality is unclear.[1][3]
How Relyvrio's Side Effects Compare to Other ALS Drugs
Unlike Riluzole (nausea, liver enzyme elevation) or Edaravone (walking issues, headaches), Relyvrio hits the gut hardest with diarrhea in 20-30% of users. It shares fatigue with many ALS meds but adds unique risks like pancreatitis not seen as prominently elsewhere.[1][4]
Why Do These Side Effects Happen?
Sodium phenylbutyrate reduces ER stress but can disrupt gut bacteria and bile acids, driving diarrhea. Taurursodiol protects mitochondria but may overload liver processing in impaired patients, raising toxicity risks.[2][5]
What If You Experience Severe Side Effects?
Stop Relyvrio and seek medical help for pancreatitis signs (severe abdominal pain, vomiting) or allergic reactions (rash, swelling). Report to FDA MedWatch; monitor liver function regularly.[1]
Long-Term Risks and Monitoring
No data beyond 24 weeks shows new risks, but ALS progression may mask effects. Monthly liver tests recommended; avoid alcohol to cut liver strain.[1][2]
Sources:
[1] Relyvrio Prescribing Information, Amylyx Pharmaceuticals (https://www.relyvrio.com/)
[2] FDA Approval Label (https://www.accessdata.fda.gov/drugsatfda_docs/label/2022/217796s000lbl.pdf)
[3] ALS patient forums and post-marketing reports via Drugs.com (https://www.drugs.com/sfx/relyvrio-side-effects.html)
[4] Riluzole/Edaravone comparisons, ALS Association (https://www.als.org/)
[5] Mechanism review, Neurology journal (https://n.neurology.org/content/99/15/678)