Tweet. There are no known adverse reactions between Plavix (Clopidogrel) and eating grapefruit, or drinking grapefruit juice. Furthermore, there is no sufficient evidence that illustrates grapefruit juice, or the fruit itself would interfere with the effectiveness of Plavix.
Other, more minor side effects include constipation, headache, dry mouth and insomnia (because the chemicals in these drugs also influence sleep patterns). Herbal diet pills, even though they're all natural, can have potentially dangerous side effects depending upon their ingredients.
The seizure treatment medication zonisamide, sometimes prescribed off label for weight loss, can cause side effects including headache, nausea and dizziness. Contact your doctor if your prescription diet pills give you headaches or cause side effects.