Thymic peptides
Thymic peptides are natural or copied fragments of proteins first found in the thymus, the gland that trains immune cells. Thymosin alpha-1 is approved in some countries for hepatitis B and as an immune booster, while thymosin beta-4 and the TB-500 products sold online are unapproved and marketed for healing. Injection-site irritation is the most common effect in published studies, and serious harms are rarely reported but also rarely looked for. The key safety point is product identity, since the peptides sold online are not the standardized materials studied in trials.