What is the nocebo phenomenon?

Some people get side effects from a drug because they know if could be a side effects. It's simply a part of being human. And we see it with many drugs. Now imagine males being warned about a drug that can cause erectile dysfunction, decreased libido and other sexual issues. How many will develop issues simply from this advanced knowledge and warning?

These are precisely the low but well known uncommon side effects of the male balding drug finasteride. How common are sexual issues from finasteride simply from the warnings? Well, a study from Italy set out to test this in 2007. Patients were divided into two groups - one group which got a warning and one which did not. 


So, what were the results?

Results showed that about three times more men reported side effects when they were given advanced waring compared to me who did not receive any such warning. Erectile dysfunction and decreased libido was reported in 31 %  and 24 % of men who received the warning compared to only 10 % and 8 % of men who were not counselled about this side effect.



The so called Nocebo Phenomenon is powerful and needs to be remembered in interpretation of all studies and evaluation of all clinical data. 



Mondaini N et al. Finasteride 5 mg and Sexual Side Effects: How many of these are related to the Nocebo Phenomenon? J Sex Med 2007; 4: 1708-12



Dr. Jeff Donovan is a Canadian and US board certified dermatologist specializing exclusively in hair loss. To schedule a consultation, please call the Whistler office at 604.283.1887

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