What should you know about niacin and rhabdomyolysis?

Rhabdomyolysis happens when damaged muscle releases substances into the bloodstream. The kidneys may be affected, so this is more than ordinary muscle soreness after exercise. Heavy exertion, crush injury, heat illness, some medicines, supplements, infections, and metabolic problems can contribute. Niacin products differ in dose and formulation, and the risk may change when they are combined with other medicines or supplements.

Symptoms can include marked muscle pain, weakness, swelling, unusual tiredness, or urine that looks dark. Symptoms may occur after exercise or another trigger, but appearance alone cannot confirm the diagnosis. Clinicians may check blood and urine tests and assess kidney function, hydration, medicines, and the likely cause.

If rhabdomyolysis is possible, stop strenuous exercise and contact a medical service promptly. Do not take another niacin dose or add supplements until a clinician reviews the product and your medicines. Bring the packaging, list of all medicines, and details of recent exercise, heat exposure, illness, or injury. Do not rely on home hydration alone when symptoms are significant.

Seek urgent care for severe muscle pain or weakness, rapidly increasing swelling, very dark or reduced urine, vomiting, confusion, faintness, or trouble breathing. Emergency assessment is especially important when symptoms follow intense exertion, heat exposure, an injury, or a new medicine. A clinician can identify kidney or electrolyte problems before they become more severe.

Could my niacin product or another medicine be contributing? Which tests do I need, and when should they be repeated? Should I stop, restart, or replace the product? When is it safe to return to exercise?