Blackheads are one of the typical symptoms of acne and can be treated with azelaic acid cream and metronidazole. Acne is a chronic inflammatory disease of the sebaceous glands of the hair follicles, which can form when the follicles become clogged with oil and shedding dead skin. Blackheads are formed when sebum and keratinocytes block the pores and oxidize and darken when exposed to air. Azelaic acid cream is often used as a topical treatment for mild to moderate inflammatory acne vulgaris, and metronidazole is an anti-Propionibacterium acnes infection, both of which have some therapeutic effects on acne. However, azelaic acid cream can cause itching, burning, stinging and other adverse reactions, and metronidazole can cause nausea, vomiting, loss of appetite and other adverse reactions. It is recommended to consult a doctor before using the medication, and it is prohibited for those who are allergic to these two.