Thinning of hair in males at your age is due to male pattern hair loss (or androgenetic alopecia) which is due to male hormone ( androgen)  and genetic effect ( as the name suggests). This condition progresses gradually to cause conversion of normal hair to thin hair causing baldness eventually. Minoxidil solution and Finasteride orally are the only medicines known to work with enough scientific proof for both. Side effects of these medicines is usually nil to minimum. Morr f contains finasteride in a solution which claims to avoid the side effects with oral finasteride but there is no enough evidence that finasteride applied as solution can work or give same results as Oral finasteride. Plus the side effects of finasteride depends on the dose and its completely reversible, so if you are taking it under guidance there is nothing to worry about.