Is topical finasteride completely free of side effects?

Topical finasteride is lower risk

Finasteride is a medication which blocks an enzyme known as 5 alpha reductase. It reduces DHT levels. Some of the side effects that are possible come from this reduction in DHT in the blood stream.  These include mood changes, sexual dysfunction, weight gain. In effort to reduce the risk of side effects there are increasing efforts around the world to create topical finasteride. Some of it is made up by compounding pharmacies. In some countries, it is commercially available (as in MorrF in India (Intas Pharmaceuticals).  

Topical Finasteride Gets Absorbed and Reduces Serum DHT

It's important for any user of topical finasteride to be aware that there is some small degree of absorption of finasteride into the blood stream even with topical finasteride. Studies have shown that the amount is low but one needs to keep in mind that if an individual is extremely sensitive to small fluctuations in serum DHT, this could still be relevant. 

Studies have suggested that with some formulations of topical finasteride about 1/10th to 1/20th of the amount gets absorbed into the blood compared tot he amount if the pills were used.  Studies have shown that topical finasteride still reduces serum DHT. Instead of reducing DHT by 70 % (as in the case of the pills), DHT is still reduced 25 %. Of course the degree of reduction is not the same as oral finasteride but nevertheless topical finasteride does reduce serum DHT.

 

Conclusion

I am not of the opinion that topical finasteride thas zero side effects. However, I am of the opinion that the chances of side effects are very low and significantly lower that oral finasteride. However, we still don't know if topical finasteride works quite as well as oral finasteride. Those "good" studies have not been done despite the rapid increase in world wide use of topical finasteride.  One must always keep in mind that there is no such thing as "standard" topical finasteride. Some pharmacies compound finasteride that can easily get into the blood stream and yet others use other chemicals in the formulation that make it more difficult for the finasteride to enter the blood stream. A variety of chemical constituents, including so called "liposomes", make it more difficult for finasteride to enter the blood all the while providing benefit in the scalp (and to the hair loss).  I always tell my patients that the topical finasteride they buy at their pharmacy may not be the same as another person buys at their pharmacy. We need to stop referring to this group of medications by the general term topical finasteride and referring to it by the specific formulation (i.e. 1% liposomal finasteride, or 0.1 % finasteride in soy phosphatidylcholine, ethanol, water). There is no such thing as standard topical fiansteride.