Peptides are marketed online as injectable compounds that promise improvements in fitness, recovery and lifespan. Influencers and biohackers often promote them as a shortcut to better health. The products have become a sizable commercial sector, with many brands offering a range of formulations. Health experts question whether the claims are backed by solid research. Safety concerns include potential side effects and lack of regulatory oversight. The article notes that consumers should weigh the limited scientific evidence before using such injectables.