How To Take Levothyroxine And Cytomel (Liothyronine) Together

In our latest question and answer, we discuss how to take both Cytomel (liothyronine) and levothyroxine together.


What is the best way to take cytomel. I am on 100mcg of synthroid and 25 of cytomel. does it work better to take it all at once with my synthroid or split the dosage.

Asked by milliron On Oct 04, 2018

Answered by
Medical Content Reviewed By PharmacistAnswers Staff

On Oct 05, 2018


It can often be difficult to coordinate medication dosing schedules, especially if you are taking one or more that are recommended to be taken on an empty stomach, with no other medication. This is often the case with thyroid replacement medications.

Levothyroxine and Cytomel (liothyronine), two thyroid replacement medications, are both recommended to be taken on an empty stomach, around 30 to 60 minutes before breakfast for optimal absorption (1, 2). However, when it comes to dosing, consistency is key in regard to getting the best and most consistent results.

What Is Levothyroxine? 

Levothyroxine, which is available as multiple brand names and in many dosage forms, is the usual and recommended treatment for hypothyroidism according to most medical guidelines (1, 2). Reasons for this recommendation include that it is:

  • Effective for treating hypothyroid symptoms in most patients
  • Relatively inexpensive
  • Generally well-tolerated
  • Dosed once daily

Levothyroxine contains T4 (thyroxine), which is converted in the body to more biologically active, T3. For most individuals, taking levothyroxine (T4) will sufficiently treat hypothyroidism but a small percentage of individuals don't efficiently convert T4 to T3. For these individuals, a mixed T4/T3 product may be preferred.

Levothyroxine is generally well tolerated and side effects are often attributable to the wrong dosage, which can manifest as symptoms of either hypothyroidism or hyperthyroidism.

What Is Cytomel (Liothyronine)?

Cytomel (liothyronine) contains T3, which is the active hormone from which the levothyroxine is converted to by deiodinase enzymes in our bodies (2).

While Cytomel is indicated and FDA approved to treat hypothyroidism, it generally isn't recommended as first line therapy by most medical guidelines. 

Successful treatment of hypothyroidism and normalization of TSH (thyroid stimulating hormone) with Cytomel alone generally requires high doses, putting some individuals at risk for hyperthyroidism in some tissues.

In addition, Cytomel often needs to be taken multiple times a day since it has a short half-life, resulting in fluctuating levels in the body. Effects of the drug can wear off fairly quickly.

If you take Cytomel once daily and notice symptoms of hypothyroidism getting worse as the day progresses, speak to your doctor about possibility splitting your dosages throughout the day. One study recommends to take Cytomel two to three times daily but if the dose cannot be divided evenly, give the larger dose at bedtime. (6)

While not a first line option for hypothyroidism, Cytomel may be an appropriate choice in those who cannot efficient convert T4 to T3 and is often used in combination with levothyroxine. A variety of  studies have shown improved symptoms and quality of life in those combining Cytomel and levothyroxine versus those taking levothyroxine alone (2, 3).

Taking Cytomel And Levothyroxine At The Same Time

It is important to talk to your doctor regarding the best time to take Cytomel and levothyroxine if both have been prescribed to you. There is no single recommended method of dosing.

The most important thing is to stay consistent! A small change in how you normally take Cytomel and levothyroxine can make a big difference in absorption and overall effect.

The most common recommendation for individuals is to take both medications at the same time, in the morning on an empty stomach, about 30-60 minutes before food with a full glass of water. If you are prescribed to take Cytomel more than once daily, subsequent doses should be taken on an empty stomach as well if possible.

In addition, some studies suggest the evening dosing of thyroid medication may provide better results and symptom control for some individuals (4, 5). Again, the most important thing is to stay consistent with dosing and pick a time that allows you to take the medication at the same time every day, in the same manner.

Be sure to speak with your doctor to work out the best dosing schedule for your situation.

About the Pharmacist

Dr. Brian Staiger Pharm.D

Dr. Brian Staiger is a licensed pharmacist in New York State and the founder of He graduated from the University At Buffalo with a Doctor of Pharmacy degree in 2010. He has been featured in numerous publications including the Huffington Post as well as a variety of health and pharmacy-related blogs. Please feel free to reach out to him directly if you have any inquiries or want to connect! He's answered thousands of medication and pharmacy-related questions and he's ready to answer yours! Office: 716-389-3076

Recent Questions