I need advice on usage of Hair 4 U Topical

Patient: I have been having a bad case of hair fall an visited a dermatologist and was prescribed with multivitamin tablets and hair4u topical solution which I was asked to massage onto the scalp twice a day, once in the morning and once in the night. My question is do I need to wash my hair before using the solution? Or can I use it in the night after washing my hair, using it in the morning and also applying oil.Also give me recommendations on how often to wash my hair.

Symptoms: Hair fall, hair thinning