Blocking testosterone (which is what spiro does) will cause the sebaceous glands to not become as effective (or effective at all). The sebaceous glands are responsible for giving your skin / hair that oily texture. This is why women have dry skin and men get acne (in general). Sebum (which is the oil secreted by the sebaceous glands) is what gives the hair the moisture it needs (and your skin some added protection against the sun, among other things).
I've found lotion to be an excellent fix for dry, frizzy hair. Frizzy hair is caused by dry hair, or by overly porous hair in a humid environment. Lotion will actually give the hair an even amount of moisture throughout the strand, enough so to make it more manageable. Careful not to apply too much, however, as you may wind up giving your hair an oily, greasy look.. which isn't that attractive either.
You can also invest a lil into getting a good deep conditioner. A good deep conditioner will smooth the cuticle (the outer portion of the hair that defines its porosity) a bit.
Also, stay away from products with alcohol in it. Alcohol will dry your hair out!!