Minoxidil may be effective for M-shaped hairline. Minoxidil is primarily indicated as a topical medication for the treatment of male pattern baldness, which is also known as androgenetic alopecia, as well as patchy baldness. M hairline is a type of hair loss that is an indication for Minoxidil. However, no medication is guaranteed to be effective and the exact efficacy depends on individual differences. Minoxidil is usually applied to the affected area of the head and then applied from the center, after which it can be massaged by hand for ten minutes, and the total amount should not exceed two milliliters per day. Side effects are mild dermatitis of the scalp, systemic adverse effects are rare, and hypotension is seen in a very small number of people. Contraindications are people who are allergic to the product. Overall, Minoxidil is still a useful first-line medication for the treatment of hair loss, but it needs to be used consistently, and if any discomfort occurs during use, seek medical attention as soon as possible. Hair loss is recommended to use the drug under the guidance of a doctor, not blindly self-medication, in order to avoid adverse effects.