How Coffee Interferes With Thyroid Medication

Many people want to drink a cup of coffee before heading to work or getting the day started. But if you do so before or within an hour after taking your levothyroxine (L-T4), you may experience reduced absorption of the drug, which makes it less effective. A thyroid drug is more likely to have consistent effects if you take it properly. In the case of coffee, drinking some too close to when you take your medication can cause you to have fluctuating thyroid hormone levels and symptoms, as well as difficulties with adjusting your dose of L-T4.

In general, it is recommended to take your thyroid pills in the morning, on an empty stomach, and that you wait an hour before eating. This goes for both the generic form of levothyroxine, as well as Synthroid, Levoxyl, Tirosint, and Unithyroid.

Caffeine and Levothyroxine Absorption

Studies have found that drinking coffee at the same time or shortly after taking your L-T4 tablets can significantly lower the absorption of the thyroid medication in your intestines.

Effects of drinking coffee in close succession to thyroid medication.

Melissa Ling / Verywell

The caffeine in coffee is believed to be the cause of this effect. Caffeine can produce an increase in intestinal motility, or intestinal movement. It may also induce an increase in the amount of fluid that flows from your body into your intestines, which results in loose stools. Both of these can make your oral medication pass through your intestines rapidly. In fact, some of the medication may leave your body in the stool before it has a chance to become absorbed into your system.

With lower absorption, the medicine will have less of the intended effect, which increases your risk of experiencing the symptoms of hypothyroidism.

Researchers have found that for patients taking levothyroxine tablets, absorption is affected by drinking coffee within an hour of taking thyroid drugs. This is why experts recommend that you wait at least 60 minutes after taking the levothyroxine to drink your coffee. 

This decreased L-T4 absorption can occur when you drink coffee, caffeinated tea, hot cocoa, or caffeinated soft drinks before or shortly after taking your L-T4, although it has been most commonly studied with coffee.

Gel and Liquid Formulations

Tirosint is a soft gel form of L-T4, and Tirosint-Sol is the liquid form. These medications are absorbed more rapidly into the body than the standard formulations. The gel and liquid forms of L-T4 were developed primarily for people who have digestive and absorptive problems or allergy issues.

Studies have also shown that you can take Tirosint and Tirosint-Sol at the same time as your coffee, with no negative impact on absorption or thyroid hormone levels.

Switching Medication

Switching your thyroid prescription to another brand or, if you're not already on one, a generic, is not generally recommended because it can cause your levels to fluctuate. However, if you are having problems with absorption or with inconsistent thyroid hormone levels while using L-T4, switching to another form may be the right solution. You can talk with your healthcare provider to see if liquid or gel forms may be right for you.

If you do switch, be sure to take your medication as directed and to follow through with any blood tests that your healthcare provider orders to ensure that you are on the right medication dose.

A Word From Verywell

The decreased absorption with coffee seems to be an issue for L-T4, and it has not been observed with other thyroid medications, such as combinations of thyroxine (T3) and triiodothyronine (T3) or antithyroid medications. Coffee and other forms of caffeine do not interfere with thyroid hormone function or increase or decrease the chances of developing thyroid disease.

It is also important to keep in mind that fiber-rich foods, calcium supplements such as calcium carbonate, and iron supplements such as ferrous sulfate can interfere with absorption of your thyroid medications, and this effect can last longer than an hour. Be sure to check with your healthcare provider or pharmacist so that you don't take any vitamins or supplements on a schedule that prevents you from getting the full dose of your thyroid medication.

Frequently Asked Questions

  • What foods and supplements can interfere with thyroid medication?

    Besides coffee, some other foods, supplements, and medications can affect how Synthroid (levothyroxine) works and make it less effective. These include:

    • Foods containing soy and cottonseed meal
    • Walnuts
    • Dietary fiber
    • Grapefruit juice
    • Iron supplements and multivitamins with iron
    • Calcium supplements and multivitamins with calcium
    • Antacids

    Check with your healthcare provider if you have questions or concerns about how your diet or supplements could affect your thyroid medicine.

  • Can you take levothyroxine in the evening?

    It may be OK but talk with your healthcare provider first. The usual recommendation is to take it on an empty stomach in the morning. However, you may be able to take it on an empty stomach in the evening, at least three to four hours after you've eaten. A 2010 study found this was just as effective as taking it in the morning.

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Article Sources
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  1. Wegrzyn NM. Malabsorption of L-T4 Due to Drip Coffee: A Case Report Using Predictors of Causation. J Acad Nutr Diet. 2016;116(7):1073-6. doi:10.1016/j.jand.2016.02.016

  2. Rao SS, Welcher K, Zimmerman B, Stumbo P. Is coffee a colonic stimulant? Eur J Gastroenterol Hepatol. 1998;10(2):113-8.

  3. Benvenga S, Bartolone L, Pappalardo MA, et al. Altered intestinal absorption of L-thyroxine caused by coffee. Thyroid. 2008;18(3):293-301. doi:10.1089/thy.2007.0222

  4. Cappelli C, Pirola I, Gandossi E, et al. Thyroid Hormone Profile in Patients Ingesting Soft Gel Capsule or Liquid Levothyroxine Formulations with Breakfast. Int J Endocrinol. 2016;2016:9043450. doi:10.1155/2016/9043450

  5. Han MA, Kim JH. Coffee Consumption and the Risk of Thyroid Cancer: A Systematic Review and Meta-Analysis. Int J Environ Res Public Health. 2017;14(2). doi:10.3390/ijerph14020129

  6. Mazokopakis EE, Giannakopoulos TG, Starakis IK. Interaction between levothyroxine and calcium carbonate. Can Fam Physician. 2008;54(1):39.

  7. Campbell NR, Hasinoff BB, Stalts H, Rao B, Wong NC. Ferrous sulfate reduces thyroxine efficacy in patients with hypothyroidism. Ann Intern Med. 1992;117(12):1010-3. doi:10.7326/0003-4819-117-12-1010

  8. Taking Synthroid the right way.

  9. Bolk N. Effects of evening vs morning levothyroxine intakeArch Intern Med. 2010;170(22):1996. doi:10.1001/archinternmed.2010.436

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