Is Your Energy Bar Messing Up Your Meds?

Six surprising medication snafus, resulting in poor workouts, bad dreams, underdosing—and maybe even an early grave.

By Stacey Colino
Rx medication prescription meds pink bottle pills pharmacy picture
Photograph: Ann Cutting

The hormonal changes that occur around menstruation can affect how quickly your body processes drugs, Legato says. During the second half of your menstrual cycle, progesterone levels rise, possibly inhibiting the stomach’s absorption of medications. “You may need to tailor the dose of your medication to the phase of your cycle,” notes Legato. For example, the anticonvulsant Dilantin is metabolized more rapidly at the beginning of the menstrual cycle than at any other time.
In addition, right before or at the very beginning of your period, shifts in the levels of estrogen and progesterone as well as cyclical changes in your immune function can also cause flare-ups in symptoms of asthma, depression, diabetes, irritable bowel syndrome, migraine or seizure disorders, among other conditions. As a result, at certain times of the month, the dose of medication that’s normally used to treat these conditions may not control your symptoms or prevent flare-ups.

PROTECT YOURSELF If you have any of those chronic health conditions, track your symptoms throughout your menstrual cycle so you can tell your doctor about cyclical flare-ups and describe how well your medication manages them. “You may need a higher dose of medicine at certain times of the month,” Legato says. Or you may need to take an additional drug at certain points in your cycle. Another tactic: Talk to your doctor about the possibility of using a hormonal contraceptive that will even out your monthly internal chemistry and thus reduce your flare-up potential.


It’s well known that drugs can interact negatively with other medications or supplements, which is why the labels or package inserts caution against taking those products simultaneously. But in a little-recognized phenomenon, certain medications can also interact with nutrients such as calcium, iron and magnesium that are found in fortified foods, boosting the chances that the treatment will either fail or produce nonoptimal results. “For example, the added minerals in iron-fortified cereal and calcium-fortified orange juice can bind with certain drugs and inhibit their absorption by the body,” explains Bethanne Brown, PharmD, RPh, a clinical associate professor of pharmacy practice at the Winkle College of Pharmacy at the University of Cincinnati. The list of drugs that interact with these foods includes commonly used antibiotics such as tetracycline, doxycycline and ciprofloxacin, and the thyroid medication levothyroxine. Also, the effectiveness of antihistamines such as fexofenadine declines if you take one around the same time you eat an energy bar that’s fortified with magnesium.

PROTECT YOURSELF If a package insert warns you not to take the drug with sources of calcium (such as supplements, antacids or dairy foods) or iron (such as supplements), you’re on notice that there could be an interaction with a fortified food, Brown says. In that case, your best bet is to put some time between the drug and calcium-fortified orange juice, fortified cereal or nutrient-charged energy bars or drinks: Take the pill an hour before the food or beverage or three hours after, which will allow your body to clear out the calcium- or iron-related ingredients.


Has your mind been playing scary movies while you’re asleep? That could be due to certain drugs you’re taking: sedatives (for anxiety or insomnia), beta-blockers (for hypertension, anxiety or migraine prevention), dopamine agonists (for Parkinson’s or restless-leg syndrome) and amphetamines (for weight loss or attention deficit disorder). What’s the connection? Because these drugs can affect the brain chemicals norepinephrine, serotonin and dopamine, they can also trigger nightmares by disrupting REM sleep, the stage during which most dreams occur, speculates Dennis F. Thompson, PharmD, a professor of pharmacy practice at Southwestern Oklahoma State University in Weatherford.

First Published August 22, 2011

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Prafulla More11.18.2011

Hi, Stacey Colino!A fantastic article from you on a very important health related issue.It is very serious to know that the effectiveness and safety of many widely used drugs are influenced by your age, weight, health, body fat and, especially, your gender.Looking at dangerous side effects of commonly used medicine One can say that The Cure is worst than disease.
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