It's important with any prescribed medication that you understand all the side effects. One that is often overlooked is whether you should eat or not with the prescribed pill or if there are any foods to avoid. So much interacts with medicine and it's not just alcohol. There are a number of foods that can get in the way of how a prescription works in the body. Here are a few common combinations to avoid. 

Grapefruit + Statins: Statins help with high cholesterol. Common medications include Lipitor or Crestor and are very dangerous to take when eating with grapefruit. This kind of juice competes with an enzyme in the body that is directly responsible for breaking down the statins in the body. 
 

Orange Juice and Antihistamines
Citrus foods can challenge how your body absorbs antihistamines too. The problem comes down to furanocoumarins, a natural compound foundin tangelos, Seville oranges  and pomelos included. Orange juice has the ability to block the work of proteins that transport allergy medicines around the body, blocking absorbption and even reducing its effect.  

Kale, Licorice,  Blood-Thinners.
Kale, collard greens, spinach, broccoli  Brussels sprouts can interfere when eaten with blood thinning medication such as Coumadin or Warfarin. These dark leafy greens are rich in Vitamin K which can increase the risk of bleeding. Vitamin K naturally helps blood to clot and can work against a blood thinner's job in your body. 

Salty Foods  Blood-Pressure Meds 
For people taking blood-pressure reducing medications, additional sodium can raise blood pressure  force the medication to work much harder.