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Someone shared a personal report about a bad reaction after injecting a peptide called GHK-Cu. They described two separate shots that at first felt normal, then a few hours later the injection site became very painful, then swollen and hardened, with a red circular spot that later turned itchy. They’re asking if anyone else has seen this and for tips. This is an individual’s anecdote, not a controlled study. GHK-Cu (glycyl-l-histidyl-l-lysine copper) is a small molecule that naturally occurs in the body and is studied for roles in wound healing, skin health, and inflammation. In supplements and experimental cosmetic or medical uses it’s often applied topically or given in small injections. It’s sometimes touted for skin repair and anti-aging. That said, real clinical use and approval for injected forms are limited; people experimenting with it often do so outside of formal medical guidance. The “study” here is really a firsthand report of two injections by the same person, not a clinical trial. The timeline they describe—no pain at injection, increasing pain over hours, then swelling, hardening, redness and later itching—is consistent with a local inflammatory or allergic-type reaction at the injection site. Because it’s only one person and the details (sterility, exact preparation, where it was injected, needle size, concentration, prior sensitivity) are incomplete, we can’t say whether the peptide itself caused this, whether the solvent or how it was prepared was to blame, or whether it was an infection. The fact the same pattern happened twice increases the chance the reaction is linked to the injected material or the method rather than random chance. Why this matters: anyone considering using GHK-Cu by injection should know local reactions are possible. For people trying DIY or cosmetic peptide injections, this shows that even small doses can cause significant local pain, swelling and skin changes. If you’re using injected peptides for skin improvement, wound care, or other off-label reasons, be cautious—these reactions are unpleasant and could signal a more serious problem like infection or an allergic reaction. Caveats and risks: this is an anecdote, not proof of a general effect. Injection site reactions can come from the peptide, the solvent, impurities, improper mixing, contamination, or technique. Infections can look similar and need medical attention. People with allergies, compromised immune systems, or poor skin circulation should be especially careful. GHK-Cu injections are not an FDA-approved standard treatment for most indications, so they’re often used without official dosing or safety data. If you get a similar reaction—severe pain, spreading redness, fever, heat, or pus—seek medical care. For milder, localized reactions, stop further injections and consult a clinician before continuing. Bottom line: this report suggests GHK-Cu injections can cause painful, swollen, red spots in some people, but it’s one-person evidence so get professional medical advice before trying or continuing injections.
Source: r/Peptides