A hair growth agent having an effective dose of a platelet dry powder and a pharmaceutically acceptable solvent and/or excipient, wherein the effective dose refers to the presence of at least 1,000 platelets in every milligram of the hair growth agent.一種毛髮生長劑,其含有效劑量的血小板乾粉及醫藥可接受之溶劑及/或賦形劑,其中所謂有效劑量,係指每毫克毛髮生長劑中,至少含1,000個血小板細胞。