Peptide Therapy: Benefits, And Side Effects Explained Are There Any Known Side Effects of Peptide Therapy? Peptide therapy, while often praised for its targeted action on cellular pathways, is not without potential adverse effects. Common mild reactions include localized pain at the injection site, transient swelling, and occasional redness or bruising that usually resolves within a few days. More rarely, patients may experience systemic symptoms such as headaches, fatigue, or low- |