Doctors recommend testosterone boosters made from natural ingredients as opposed to those that are made from chemicals because they have lesser side effects. It is also not recommended for people to take testosterone supplements unless they have a direct advice from a doctor. Many people can still do better without it. Boosting strength is something that can be achieved naturally if a little effort and dedication is applied.
A large number of people that have taken testosterone boosters have found them to be very helpful, so they cannot be completely disregarded. However, the reaction differs among different bodies.