Minoxidil 5% is the most commonly used strength for the face, as the higher concentration in the 10% can cause more irritation and reactions. Additionally, 2% and 5% are the only strengths currently approved by the FDA. You can try starting with 5% and see how you go, giving it at least six months. If you find you're not getting results, you can try the 10%, but be very wary of side effects.