There are a number of side-effects due to Bontril being a stimulant. People with heart disease or high blood pressure should not take Bontril. It can cause insomnia, restlessness, anxiety, headaches, dizziness, dry mouth, diarrhea, or constipation.

Bontril is habit forming. You can become psychologically and physically dependent on it.

People who use Bontril will lose weight in the short term. But, in the long term they gain it back.