Rogaine (minoxidil) is an over-the-counter (OTC) topical medication that helps with short-term hair growth in adults ages 18 and older. Rogaine is most effective for people under 40 years of age whose hair loss is recent. It is essential to know that Rogaine does not affect receding hairlines and does not cure baldness. 

A person will never get back a full head of hair with Rogaine or any other topical hair loss solution. And people take Rogaine even though they learn that if they get some new hair, it is lost within a few months after the drug is stopped.

How Rogaine helps with hair growth is unknown. It's thought to work by influencing the hair cycle. Rogaine might lessen the time between the telogen phase, when the hair stops growing and eventually falls out and the anagen phase, which is the hair growth phase.

Rogaine is thought to also work by opening potassium channels—proteins that form a tunnel to allow the passage of potassium—in the hair follicle. By opening potassium channels, Rogaine might block calcium into the hair cell. Without calcium, the epidermal growth factor (EGF), a type of protein, will not prevent hair growth.

Rogaine is also thought to raise the activity of 17 beta-hydroxylated dehydrogenase (17β-HSD)—involved in the final step of making testosterone—in the dermal papilla cells of a balding scalp. 

The following is not a complete list of side effects, and others may occur. Common side effects of Rogaine include;

Changes in hair color or texture, itchiness, skin irritation, skin rash, and skin redness.

There are also some severe side effects; 

serious side effects; chest pain, dizziness, fast heartbeat, feeling faint, swelling of hands and feet, unwanted facial hair, and weight gain for no reason.

Rogaine has many harmful side effects and won't give you a full head of hair. And the side effects should be enough of a warning to stay away from the product.