We can rarely, if ever, be certain about the effects of a treatment as there will always be limitations and risks involved.
When considering treatment options, it is important to investigate any negative/harmful effects they could have. Very few treatments are always safe.
Medicines can have side effects and adverse reactions can occur. It is easy to ignore possible negative effects when focussing on trying to cure illness, but it is important to consider all desired and undesired consequences of the treatments available in order to make an informed decision. Primarily, a veterinary professional must ensure that their advice follows a “do no harm” approach.
BEWARE if treatments claim to be 100% safe or do not mention any potential negative effects.
REMEMBER: All treatments can be harmful as well as helpful.