What is the difference between Liothyronine and Levothyroxine?

Key Takeaways

1. Liothyronine and Levothyroxine: Both medications are used to treat hypothyroidism (an underactive thyroid), but they have different half-lives, dosages, and specific uses.

2. Usage and Dosage: Liothyronine is typically taken with or without food, while Levothyroxine should be taken on an empty stomach.

3. Side Effects and Costs: Both medications can cause temporary hair loss, and they are available with a prescription, with varying costs depending on the strength and quantity.

When it comes to treating hypothyroidism (an underactive thyroid), Liothyronine and Levothyroxine are two commonly prescribed medications. Although they serve a similar purpose — providing synthetic thyroid hormones to balance the body’s metabolism — they have important differences. This guide will explore the key distinctions between Liothyronine and Levothyroxine, including how they are taken, their costs, side effects, and when each one is typically used.

What is Liothyronine?

Liothyronine is a synthetic form of the thyroid hormone T3 (triiodothyronine). It is primarily used to treat hypothyroidism, a condition where the thyroid does not produce enough thyroid hormones to regulate essential body functions such as metabolism.

How Does Liothyronine Work?

Liothyronine works by supplementing the thyroid hormone T3, which plays a crucial role in the regulation of metabolism, energy production, and overall bodily functions. By boosting T3 levels, Liothyronine helps to reverse symptoms like fatigue, weight gain, dry skin, and depression, all of which are common in individuals with hypothyroidism.

What is Levothyroxine?

Levothyroxine, on the other hand, is a synthetic version of T4 (thyroxine), the precursor to T3. Once administered, the body converts T4 into T3, which then performs the same metabolic functions. Levothyroxine is the most commonly prescribed treatment for hypothyroidism in the UK.

How Does Levothyroxine Work?

Levothyroxine increases the amount of thyroid hormone in the body by providing synthetic T4. This hormone is then converted into T3 within the body, helping to restore proper thyroid function and alleviate symptoms of hypothyroidism such as weight gain, fatigue, and cold intolerance.

Can Liothyronine and Levothyroxine Be Taken Together?

While both medications are used to treat hypothyroidism, it is essential to follow the prescription your doctor provides. Liothyronine and Levothyroxine should not be taken together unless specifically prescribed by your healthcare provider. Typically, doctors will prescribe one or the other based on your thyroid function and individual needs. However, in some cases, a doctor may prescribe a combination of both medications, especially if one is not sufficiently managing symptoms.

How to Take Liothyronine and Levothyroxine

Can You Take Liothyronine with Food?

Liothyronine can be taken with or without food, as food does not significantly affect the absorption of the medication. However, it’s essential to take it at the same time every day to maintain consistent thyroid hormone levels.

Can You Take Levothyroxine with Food?

Levothyroxine, however, should not be taken with food. It should be taken on an empty stomach at least 30 to 60 minutes before eating. This ensures the body can fully absorb the medication and produce the required thyroid hormones. Additionally, avoid consuming caffeine shortly after taking Levothyroxine, as it may interfere with the medication's absorption.

Cost and Availability

Both Liothyronine and Levothyroxine are available in the UK only with a prescription. The cost of these medications varies depending on the strength and quantity prescribed.

How Much Does Liothyronine Cost?

Liothyronine is typically prescribed in 25mcg, 50mcg, and 75mcg doses. The price will depend on the quantity and the prescription. It is generally considered more expensive than Levothyroxine, but it can be purchased online from PharmXtra with a valid prescription.

How Much Does Levothyroxine Cost?

Levothyroxine is available in various strengths, such as 25mcg, 50mcg, and 100mcg, and is typically less expensive than Liothyronine. It is available from PharmXtra, but you will need a prescription to purchase it.

Can I Get Liothyronine or Levothyroxine on the NHS?

If you have hypothyroidism and are prescribed either Liothyronine or Levothyroxine, you may be entitled to free prescriptions through the NHS, especially if you hold a medical exemption certificate. If not, you will need to pay the standard prescription fee.

Effectiveness and Duration in the Body

How Long Does Liothyronine Stay in Your System?

Liothyronine has a half-life of approximately 12.5 hours, which means it will take around that time for half of the drug to leave the body. The full elimination time can vary depending on the individual's metabolism and kidney function.

How Long Does Levothyroxine Stay in Your System?

Levothyroxine has a half-life of around 6-7 days, but this can vary depending on factors like age, weight, and any other medications being taken. Its presence in the system will typically last longer than Liothyronine due to the slower conversion from T4 to T3.

Side Effects and Precautions

Does Liothyronine Cause Hair Loss?

Some people may experience temporary hair loss when starting Liothyronine, as their body adjusts to the new thyroid hormone levels. If this persists, consult with your healthcare provider for alternative treatments or dosage adjustments.

Does Levothyroxine Cause Hair Loss?

Similar to Liothyronine, Levothyroxine may cause temporary hair loss during the adjustment period. However, this should resolve once your thyroid hormone levels stabilise.

Can Liothyronine or Levothyroxine Cause Weight Gain?

Both medications are used to treat underactive thyroid conditions, which can lead to weight gain. Once treatment begins, many patients experience weight loss as their metabolism improves and thyroid function normalises.

Are Liothyronine and Levothyroxine Gluten-Free?

Both Liothyronine and Levothyroxine are generally gluten-free, but it’s always important to check the ingredients list of the specific brand you're using, as formulations may vary.

Pronunciation

• Liothyronine: Lee-oh-thy-ro-neen

• Levothyroxine: Lev-oh-thy-rox-een

Final Thoughts

Both Liothyronine and Levothyroxine are essential treatments for managing hypothyroidism, and while they work similarly, they differ in terms of their action, dosage, and side effects. Liothyronine acts more quickly but has a shorter half-life, whereas Levothyroxine works more slowly and has a longer duration in the system. Always follow the prescription given by your doctor, and do not take both medications unless advised by a healthcare professional.

For both medications, it’s crucial to take them as directed to achieve the best possible results for managing your thyroid condition. If you have any concerns or experience side effects, consult with your healthcare provider for further guidance.

Medically Reviewed by:
Dr. Irfan Siddique MBBS
GMC reference no: 7694522
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Sources

• NHS - About Tadalafil

• GOV.UK - MHRA Reclassifies Cialis Together Tablets