Actually, There’s a Right Time to Take “Once a Day” Meds

When it comes to your medications for depression, allergies, heartburn, and more, timing is everything.

The instructions on the pill bottle may simply say “once a day.”

Claire Benoist for Reader's Digest

But because of your circadian rhythm—the biological clock that governs sleep, hormone production, and other processes—your body doesn’t respond to medications in the same way at different times of the day.

“Some drugs are not as effective or as well tolerated if they’re taken at the wrong biological time,” says Michael Smolensky, adjunct professor of biomedical engineering at the University of Texas at Austin. “It’s not that they’re not effective at all, but they’re certainly much less effective or tolerated.”

Now a cutting-edge field called drug chronotherapy advocates syncing your medication regimen with your circadian rhythm to maximize effectiveness and minimize side effects. Here are the best times to take meds based on chronotherapy and other factors. (Note: Never change your drug routine without first talking to your doctor or pharmacist.)

Best in the morning: Depression meds

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Disrupted sleep is a common side effect of some SSRIs (selective serotonin reuptake inhibitors), which is why experts often recommend that patients take them when they wake up.

Best in the morning: Osteoporosis meds


Your body doesn’t easily absorb bisphosphonate drugs, such as Boniva and Fosamax. So doctors advise taking them on an empty stomach first thing in the morning with a glass of water, then waiting an hour before eating, drinking, or taking other drugs or supplements.

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Best around dinnertime: Heartburn meds

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The stomach produces two to three times more acid between 10 p.m. and 2 a.m. than at any other time of day. If you’re on an acid-reducing H2 medication such as Pepcid or Zantac, take it 30 minutes before dinner. This controls stomach acid during the overnight period, when secretion reaches its peak.

Best around dinnertime: Allergy meds


Hay fever typically worsens at night and feels most severe in the morning, when levels of symptom-triggering histamine are highest. Once-daily antihistamines, such as Claritin, reach their peak eight to 12 hours after you take them, so using them at dinnertime means better control of morning symptoms. (Take twice-a-day antihistamines in the morning and evening.)

Best before bedtime: Cholesterol meds


Cholesterol production in the liver is highest after midnight and lowest during the morning and early afternoon, so statins are most effective when taken just before bedtime.

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Best before bedtime: Blood pressure meds


Blood pressure is typically higher in the day and lower during sleep. But many people with high blood pressure don’t exhibit this nighttime dip, especially as they get older. This is a risk factor for stroke, heart attack, and kidney disease. That’s why experts advise taking certain blood pressure–lowering drugs at bedtime, to normalize daily blood pressure rhythm and decrease these risks. ACE inhibitors and ARBs are most effective when taken at this time.

Timed to symptoms: Osteoarthritis meds


According to French researchers, it’s best to take NSAIDs, such as naproxen and ibuprofen—the most widely used meds for osteoarthritis—approximately six hours before pain is at its worst, so they’ll kick in at the appropriate time. If you’re prone to afternoon pain, take meds between mid-morning and noon; for evening pain, schedule them for mid-afternoon; and for nighttime pain, take them with your evening meal.

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