Rogaine is available in two strengths--2 percent and 5 percent, with the 5 percent product recommended only for men. Women tend to experience better results with the 5 percent product, but it can cause hair growth on the forehead. The higher-strength Rogaine also is more likely to cause side effects. Rogaine contains the active ingredient minoxidil, which is classified as a potassium channel opener medication.
Skin, Hair and Eyes Side Effects
The most common side effects associated with Rogaine include skin reactions and unwanted hair growth, as noted by Drugs.com. Some people experience dryness, scaling, eczema, itching, irritation or redness at the treated area. Side effects also may include increased facial hair growth, and changes in the texture or color of existing hair. Additionally, there have been reports of eye irritation or burning, and decreased visual clarity.
Although unlikely, some people may experience an allergic reaction to Rogaine. Signs as listed by Drugs.com include a rash or hives, itching, trouble breathing, tightness in the chest, and facial or mouth swelling. Development of these symptoms while using Rogaine should be considered a medical emergency. Symptoms similar to hay fever (allergic rhinitis) also are possible.
Minoxidil is prescribed as an oral drug to lower high blood pressure. If a person applies too much topical Rogaine, excess absorption might occur, creating side effects associated with the oral drug. This is rare, but side effects due to absorption may include rapid weight gain and fluid retention in the ankles, lower legs, hands or stomach (edema). Other rare side effects due to minoxidil absorption, as listed by the Mayo Clinic include chest pain, changes in blood pressure, rapid or irregular heartbeat, heart palpitations, headache, dizziness, faintness and lightheadedness. An increase in body hair also could occur.
Some Rogaine users have reported gastrointestinal effects including diarrhea, nausea and vomiting, according to Drugs.com. These effects are rare and may be associated with drug absorption.