Hairgaine is a topical spray that has two preparations: For Men (the one with green) and For Women (with pink). Hairgaine has minoxidil as an ingredient. Primarily, minoxidil has anti-hypertensive effect (especially in the oral form). Its side effects include the promotion of hair re-growth and darkening of fine body hair. For men, it has 5% minoxidil and for women, it has 2% minoxidil.
It is better to use the product for women for better results. Like how it is for the men's topical spray, the spray for women is specially formulated to work with the hormones and enzymes of women.
Used as a topical spray for the mother, Hairgaine topical solution has very little risk for breastfed the baby. However, this data shouldn't be the only basis for clearance. Inform the pediatrician prior to using this product.