There is no such thing as a wonder drug in this world. Every drug has its own side effects. This is because God has not deemed it proper to create all humans alike. Every human being is different from the other in one respect or the other. In fact even twins who are born at the same time, from the same womb too exhibit different qualities and have known to exhibit quite opposite reactions to a single drug. This is the beauty of nature and one cannot argue with the forces of nature. If this is true of twins, would it not be a hundred times truer of people as diverse as you and me? Thus the same drug has a capacity of showing different properties in different individuals. However all said and done, it is true that biotin side effects have by and large been minimal. The most common side effect of biotin is the breakout of cystic acne on the chin and jaw lines of certain types of body constitutions. One way of reducing this is to maintain correct dosage.
Biotin is a water soluble drug and hence one should consume lots of water. One can also consume vitamin B supplements to avoid acne. You can also take a multivitamin tablet instead of vitamin B supplements. Anything in excess is bad. This applies to Biotin also. Yes, it is agreed that Biotin is good for hair growth. But if this results in disfiguration of the face, is it really worth risking it for long periods? On the contrary one could take the recourse to natural ways of augmenting biotin supply. One can regulate diet by inclusion of green leafy vegetables etc as this natural way of obtaining biotin is any way much better than consuming it in the drug form.