Even a virulent poison can be converted into an excellent medicine when prepared and administered using the right methods. Conversely, even a good medicine may act as a potent poison if improperly administered.
Therefore an intelligent man who desires health and long life should not take any medicine prescribed by a physician who is a complete stranger to the application of medicines.
दुःखिताय शयानाय श्रद्दधानाय रोगिणे| यो भेषजमविज्ञाय प्राज्ञमानी प्रयच्छति ||१२९||
Denouncing of quacks: The vainglorious and charlatan person, the quack, if administers medicines to the ailing bed-ridden patient who has implicit faith in him,
such a quack is considered one who totally evades his duty, sinful, wicked and death incarnate. Even just by conversing with such quack may lead a person to hell.