Thank you for your question. Blackheads are a type of acne called comedones, and in my experience, the best way to treat comedones is with a topical retinoid, such as Retin-A, tretinoin, adapalene, Differin, etc. The purpose of the these medications is to gently exfoliate your skin to bring the comedones to the surface of the skin for removal. Alternative therapies include facials, chemical peels, or extractions. Hydrocortisone will not be effective because it is a steroid, which decreases inflammation. I highly recommend you consult with a board certified dermatologist to have your skin evaluated and to discuss treatment options that best suits your skin. Take care and good luck.