a cup of coffee, drinking coffee, chances of heart failure, decaf coffee

When was the last time you read a manual? Most of us are so impatient that we skip straight to plug and play. That’s true whether it’s a computer program, a cell phone or a rental car.

Taking pills is no exception. Most people don’t take time to consult a pharmacist when they pick up a prescription. If they get printed information in the bag, chances are it gets filed or tossed but not read carefully.

How Should You Take Your Pills?

This could be disastrous because for some medicines it makes a difference how and when you take them. Most of us are busy, so it is completely understandable that we swallow our pills first thing in the morning, often with breakfast, and get on with our day. What we eat (bacon and eggs, oatmeal or a bran muffin) and what we drink (orange juice, coffee or water) can profoundly influence how our drugs work.

Synthroid and Coffee Don’t Mix:

Consider levothyroxine (Synthroid) as an example. It is one of the perennial top drugs in the pharmacy, used to treat an underperforming thyroid gland.

Patients are usually instructed to take this medication first thing in the morning, before breakfast. How long before breakfast? The prescribing information recommends 30 minutes to an hour before breakfast.

Why? Drinking coffee, as so many of us do at breakfast, reduces the rate and extent of absorption of the levothyroxine tablet (Thyroid, March, 2008).

What About Supplements?

There are other hazards lurking in breakfast as well. A survey of people taking levothyroxine found that half of them were also taking calcium or iron supplements, which can interfere with Synthroid absorption (Drugs in R&D, March, 2016). Orange juice fortified with calcium can also reduce levothyroxine absorption. One-fifth of these folks did not wait at least half an hour after taking their thyroid pill before eating breakfast.

High-Fiber Breakfast Could Be Trouble:

More than two-thirds reported eating high-fiber foods such as bran flakes or fiber bars or foods high in soy such as soy sausage or soy milk more than twice a week. These foods are also believed to interfere with levothyroxine absorption.

Other Food-Drug Interactions:

Sticking with breakfast but looking at a different medication, we find that the absorption of the beta blocker blood pressure pill atenolol can be halved if it is taken at the same time as tea (Frontiers in Pharmacology, online June 29, 2016).

New food and drug interactions are being discovered all the time. One recent research report shows that the diabetes drug repaglinide (Prandin) may be metabolized more slowly if the person has consumed the non-sugar sweetener stevia (Food and Chemical Toxicology, Aug., 2016).  Since people with diabetes often use non-sugar sweeteners, this combination could lead to unexpectedly low blood sugar.

Watching Out for Grapefruit (and Other Foods):

Other food and drug interactions are better known. Physicians and pharmacists are aware of a number of medications that can be affected by grapefruit or grapefruit juice.

Grapefruit boosts the effect of the cholesterol-lowering drugs atorvastatin, lovastatin or simvastatin. For some people that may increase their risk for side effects.

Other foods that can affect certain medicines include cranberries, mango, avocados, green leafy vegetables, apple juice and green tea. It makes sense to find out whether a medication you are taking could be affected by the foods you eat or the beverages you drink. You can learn more from our free online Guide to Drug and Food Interactions.

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  1. Don

    Another vote for taking levothyroxine during the early morning hours. I take it at 2 am so there is no interference with food. I’ve been doing this for several years now. About a year after I started the early morning dosage the doctor tested my levels and had to reduce my dosage from 137 to 125 mcg.

    • Hank

      Yep, middle of the night works well for Synthroid. Got to get up to pee anyhow. Then put the bottle into a drawer for the rest of the night, so if I forget I took it and get up again, I have that reminder.

  2. Grace

    “Since people with diabetes often use non-sugar sweeteners, this combination could lead to unexpectedly low blood sugar.” This is taken from your statement about Prandin and how you eat your breakfast. Is this a typo of or did I miss something? If it slows down Prandin absorption it would seem that BS would be high????

    • Joe Graedon

      It slows metabolism and excretion of Prandin, not absorption. Sorry we weren’t clear.

  3. mary

    I solved the problem by taking my levothyroxine about 4 am when I get up for a bathroom run. It’s well absorbed by the time I get up about 7 am. I must have a snack at bedtime and I want coffee immediately upon arising, so this works best for me. I have been doing this for about 3 months and can tell a difference.

  4. PP

    Get Dr. LowDog’s Book, Fortify Your LIfe, and take the time to analyze what you need for supplements, their interactions, and the best time to take both them and your medications. It will take a bit of time and effort, but you will have the confidence of knowing what you are taking, when and why.

  5. Florence B.
    Round Rock

    You mention in this article that a high fiber diet breakfast could interfere when taking levothyroxine it would affect the absorption of this medicine. What you did not mention was how much time should you wait once you take levothyroxine in the AM and you can have a high fiber breakfast? You mention a half hour to an hour on the other items noted, but not the same time span for a high fiber breakfast?


    would like to have readers’ comments

  7. rick

    The article should read is your medications upsetting your breaakfast!

  8. Emma

    Even worse, my interactions RE prescriptions are all on line and I receive drugs by mail as do so many of us today.

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