Following topical application, an average of about 1.4% of the total applied dose is absorbed from the normal intact scalp. Topical Minoxidil absorption is increased by increasing the  dose applied, increasing the frequency of dosing and decreasing the barrier function of the stratum corneum. Serum Minoxidil levels and systemic effects resulting from the administration of topical Minoxidil are governed by the drug’s absorption rate through the skin. Following cessation of topical dosing, approximately 95% of the systemically absorbed drug is eliminated within 4 days. Minoxidil and its metabolites are excreted principally in the urine.

For the best results, Minoxidil topical solution should be allowed to remain on the scalp for about 4 hours before washing. The night-time application should be done 2-4 hours before going to bed to allow the solution to dry out. Minoxidil topical solution should not be massaged into the scalp, but applied lightly. A hair dryer should not be used to speed up the drying of the solution as it may decrease the effectiveness. Minoxidil topical solution should not be mixed with any hair oil. The drug should not be used more than two times a day, or be taken orally or applied to any other part of the body to avoid the risk of adverse effects and unwanted hair growth. More frequent use or longer application time have no effect on hair growth. In case of missing any daily applications of Minoxidil topical solution, the patient should continue with the next application.

Hands should be washed immediately if Minoxidil topical solution is applied with the fingertips. Clinical experience with Minoxidil indicates that twice-daily applications for 4 months or more may be required before there is evidence of hair growth. To arrest hair fall, Minoxidil topical solution should be used for not less than 45 days. Depending upon the severity of hair loss or type and extent of baldness, particular strength of Minoxidil topical solution may be selected.

• Patients with cardiac abnormalities
• Children below 18 years of age
• Patients using occlusive dressings or other medicines on the scalp
• Patients with red, inflamed infection, or irritated or painful scalp (including psoriasis & sunburn)

Signs and symptoms of Minoxidil overdosage would primarily be cardiovascular effects associated with sodium and water retention, and tachycardia. Fluid retention can be managed with appropriate diuretic therapy. Clinically significant tachycardia can be controlled by administration of a beta-adrenergic blocking agent.