Munson Health
 
Food and Medicine Interactions

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by Shuman J
a pill with silverware Most of us have heard that certain medicines, when taken together, can be potentially harmful. But what about food and medicine? What possible harm could come from eating a cheese sandwich after taking an antibiotic? You may be surprised to learn that certain foods can dramatically affect your medicines.
Knowing how and when to take your medicines can eliminate or reduce interactions between food and drugs. Your pharmacist and your doctor can provide you with the most up-to-date information about these interactions.
Take this quick quiz to check your knowledge of food and drug interactions.

True or False?

Answer true or false for each of the following eight questions.
  1. Medicine should always be taken with meals.
  2. Only prescription drugs interact with food.
  3. It is safe to take my medicines with a glass of milk.
  4. I take high blood pressure medicine. Therefore, I should use a potassium-containing salt substitute.
  5. Mineral oil is a harmless, gentle laxative.
  6. Any pharmacy can fill my prescriptions.
  7. Grapefruit juice is a harmless, healthy source of vitamin C.

How Did You Do?–The Answers

4. I take high blood pressure medicine. Therefore, I should use a potassium-containing salt substitute—False
This can sometimes be a dangerous misconception. Some blood pressure medicines (eg, furosemide) cause you to lose potassium, so your doctor may prescribe a potassium supplement. However, other classes of blood pressure medicines actually prevent potassium loss. If you take potassium-sparing diuretics or ACE inhibitors, avoid liberal use of salt substitutes that contain potassium. Excessive use of these products causes an accumulation of potassium, which can lead to severe complications that can threaten your health or life.
7. Grapefruit juice is a harmless, healthy source of vitamin CFalse
Grapefruit juice is healthy on its own, but it can interact with numerous medicines, potentially reducing their effects or increasing the risk of toxicity.

Other Food and Drug Issues

In addition to food and drug interactions, certain medicines also affect taste, sensation, and appetite. For example, penicillin can make foods "taste funny." Antihistamines and certain antidepressants can cause dry mouth, making it hard to chew and swallow. Certain pain medicines and iron supplements are a frequent cause of constipation.
How do you know when and how medicines should be taken? Read the directions printed on the container and ask your doctor or pharmacist. Food and drug interactions are almost always avoidable or manageable.
To keep food-drug interactions at a minimum, follow these tips:
  • If you experience any unpleasant new symptoms after taking a new medicine—or one you have been taking for a while—tell your doctor.
  • When a new medicine is prescribed for you, tell your doctor and pharmacist about any other medicines you routinely take, including herbal remedies, vitamin supplements, and nonprescription drugs.
  • Let your doctor know if you follow a special or restricted diet. Kosher diets have an unusually high sodium content, while traditional Asian diets may be high in both sodium and calcium. These factors may affect the types or even the brands of drugs prescribed for you.
  • Always take your medicine at the time and in the manner prescribed. Taking too much or stopping too soon can be dangerous.
  • With each medical check-up, review your medicines, lifestyle, and dietary habits. If you have recently lost weight or become a vegetarian, your medicine doses may need to be changed.
 

RESOURCES

FoodSafety.gov
http://www.foodsafety.gov

US Food and Drug Administration
http://www.fda.gov/

 

CANADIAN RESOURCES

Canadian Institutes of Health Research
http://www.cihr-irsc.gc

Health Canada
http://www.hc-sc.gc.ca/

 

References


Antidepressant medication overview. EBSCO DynaMed website. Available at: http://www.ebscohost.com/dynamed. Updated March 28, 2012. Accessed July 7, 2012.


Antihypertensive medications overview. EBSCO DynaMed website. Available at: http://www.ebscohost.com/dynamed. Updated May 29, 2012. Accessed July 7, 2012.


Avoid food-drug interactions. National Consumer League website. Available at: http://www.natlconsumersleague.org/health/146-food-drug-interactions/442-avoid-food-drug-interactions. Accessed July 7, 2012.


Drug interactions: what you should know. Center for Drug Evaluation and Research website. Available at: http://www.fda.gov/Drugs/ResourcesForYou/ucm163354.htm. Updated April 30, 2012. Accessed July 7, 2012.


Mineral oil. EBSCO DynaMed website. Available at: http://www.ebscohost.com/dynamed. Updated December 14, 2011. Accessed July 7, 2012.


Tetracycline. EBSCO DynaMed website. Available at: http://www.ebscohost.com/dynamed. Updated December 14, 2011. Accessed July 7, 2012.

 

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