if you have money to waste then put what you like on your hair, but forget about making it thicker or stopping it falling out as it is very unlikely to help.
There is nothing that you can put on your hair to make it thicker, that is decided by your genes.
There are products that can make it look or feel thicker, all these do is put a coating on the hair follicle, as normal conditioners do to make it feel/look shiner. These 'thickening products leave the hair dull and ofter slightly sticky.
A good quality hair cut can give the same elusion of thickness without damaging your hair.
Our hair thickness results from a combination of both the size of the follicles themselves and how many of them line our scalp. The size of the follicles determines if the individual hair strands are thick or thin. Large follicles produce thick hairs. Small follicles produce thin hairs. It is that simple!
Equally important to our hair thickness, the number of follicles on our scalp determines the actual number of hairs crowning our head. Lots of hairs equal thick hair. Sparse hair equals thin hair. On average, our heads are covered with over 100,000 follicles!
Hair tends to grow more quickly in the summer months because of the warmth, head massage can increase the blood supply to the head, so can help