What Is the Best Time to Take Your Thyroid Medication?

Should You Take Thyroid Drugs in the Morning or at Night?

Woman holding pills
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If you are on thyroid hormone replacement medication, the standard guidelines recommend that you take your thyroid pill first thing in the morning, on an empty stomach, and wait at least an hour before eating or drinking coffee. You should also wait at least three to four hours before taking any supplements that contain iron or calcium, calcium-fortified juice, or cow’s milk. The key is consistency, taking your thyroid pill around the same time each day, and in the same way.

But two important studies—a study published in the journal Clinical Endocrinology, and a follow-up larger randomized trial reported in the Archives of Internal Medicine—have found that taking the same dose of levothyroxine (i.e., Synthroid or Levoxyl) at bedtime, as compared to first thing in the morning, may be better.

The studies were prompted by the observation that some patients had improved thyroid hormone profiles improved after they switched from taking their levothyroxine in the morning, to bedtime.

Clinical Endocrinology reported on a small pilot study, which looked at the impact on thyroid hormone profiles by changing the time levothyroxine was taken from early morning to bedtime. They also evaluated the impact of this change on the circadian rhythm of TSH and thyroid hormones and thyroid hormone metabolism. The study, while small, was fairly conclusive in its findings, which the researchers said were “striking” and which have “important consequences for the millions of patients who take l-thyroxine daily.”

Researchers reported that taking medication at bedtime, rather than the morning, results in “higher thyroid hormone concentrations and lower TSH concentrations.” TSH decreased and Free T4 levels rose in all patients by changing thyroxine ingestion from early morning to bedtime and T3 levels rose in all but one subject.

And TSH decreased irrespective of the starting TSH levels, suggesting better absorption of the thyroid medication when taken in the evening. Interestingly, the researchers found that the circadian TSH rhythm—the typical daily fluctuations of TSH that occur during a 24-hour period—did not vary.

Why Taking Thyroid Medication at Night May Improve Absorption

The researchers suggested several explanations for the results:

  • Even when waiting for at least 30 minutes to eat, breakfast may be interfering with the intestinal absorption of levothyroxine. 
  • “Bowel motility is slower at night,” which means that it takes longer for the levothyroxine tablet to transit through the intestinal system, resulting in longer exposure to the intestinal wall, and therefore, better absorption and uptake of the medication.
  • The conversion process of T4 to T3 may be more effective in the evening.

The researchers have suggested that given the results of this study, a large double-blinded randomized study was needed to confirm their results.

That study was conducted and the results were reported on in the Archives of Internal Medicine. The study was a randomized double-blind crossover trial. Ninety patients completed the trial, which involved a 6-month period of taking 1 capsule in the morning and 1 capsule at bedtime, with one capsule active levothyroxine, the other placebo, and a switch at the three-month point.

The researchers evaluated thyroid hormone levels, as well as creatinine levels, lipid levels, body mass index, heart rate, and quality of life parameters.

The researchers found that the patients taking nighttime levothyroxine had a drop in TSH of 1.25, a significant change. The free thyroxine (free T4) level went up by 0.07 ng/dL, and total triiodothyronine (total T3) went up by 6.5 ng/dL. According to the researchers, there were no significant changes in the other factors measured.

The researchers concluded that, given the improvement in thyroid hormone levels, physicians should consider prescribing levothyroxine to be taken at bedtime.

What Are the Implications for You as a Thyroid Patient?

Taking medication at bedtime instead of in the morning could have major implications for you and many thyroid patients.

These studies confirm what many patients anecdotally have been reporting for years: they feel better if they take their thyroid medication in the evening, rather than the morning.

You may want to talk to your practitioner about changing the time you take your levothyroxine (i.e., Synthroid, Levoxyl, Tirosint) to bedtime, versus morning. And if you decide to change to taking your thyroid medication in the evening, be sure to have your thyroid levels evaluated—six to eight weeks is a reasonable timeframe—after you’ve made the switch. The blood test results, along with any improvements or worsening of symptoms, will help you and your doctor to determine if you need to adjust the dosage or timing of your medication.

What About Natural Thyroid and T3 Medications?

These studies were conducted with levothyroxine, a synthetic form of the long-acting T4/thyroxine thyroid hormone. This form of the hormone must first be converted in the body to the active form (T3), and this can take days. Thyroid drugs that contain T3—such as Cytomel, and the natural desiccated thyroid drugs like Nature-throid and Armour Thyroid—are used directly by the body within hours. These drugs were not evaluated in the study, and it's not known if medications containing T3, or natural desiccated thyroid drugs would be better absorbed at night.

Anecdotally, some thyroid patients have reported improvement in symptoms when taking some or all of their T3-based thyroid hormone replacement medications in the evening. But some thyroid patients also find that if they take a medication with T3 later in the day or in the evening, the slight stimulatory effect of the T3 medication can make it difficult to sleep.

So keep in mind that while it's possible that if similar studies were conducted with T3 drugs, the results would be similar, but there is a chance that it would impact sleep quality in some patients. You should only make such a change after discussing it with your doctor.

Some doctors have suggested that patients who take T3 medications use a time-released or sustained release formulation of T3, or split their doses and take their medication several times throughout the day. This approach seems to minimize sleep interference.

Again, if you do make a change to how you take your T3 thyroid medication, you'll want to have a reevaluation of blood levels and symptoms after several weeks, to determine if you need to adjust the dosage or timing of your medication.

A Word From Verywell

If you and your physician decide to change to taking your thyroid medication in the evening, be sure to have your thyroid levels evaluated around 8 to 12 weeks after you've made the switch. The blood test results, along with any improvements or worsening of symptoms, will help you and your doctor determine if you need to adjust the dosage or timing of your medication.


Bach-Huynh, T., Nayak, B. et al. "Timing of Levothyroxine Administration Affects Serum Thyrotropin Concentration." Journal of Clinical Endocrinology and Metabolism. 2009 Oct; 94(10): 3905–3912. Published online 2009 Jul 7. doi:  10.1210/jc.2009-0860

Bolk, Nienke MD; et. al. "Effects of Evening vs Morning Levothyroxine Intake: A Randomized Double-blind Crossover Trial." Archives of Internal Medicine. 2010;170(22):1996-2003.

Rajput, R. et. al. "Can Levothyroxine Be Taken as Evening Dose? Comparative Evaluation of Morning versus Evening Dose of Levothyroxine in Treatment of Hypothyroidism." Journal of Thyroid Research. 2011.