liothyronine sodium at a glance
Medicine class
Thyroid hormone replacement; synthetic T3.
Usual role
Severe or acute thyroid-hormone deficiency and selected specialist-led treatment.
Available forms
Selected products include tablets, hard capsules, oral solution and an intravenous hospital formulation.
Monitoring
Thyroid function and symptoms are monitored; cardiac monitoring may also be needed.
What is liothyronine sodium used for?
Selected UK products are licensed for severe thyroid-hormone deficiency and related thyroid-treatment settings.
Severe chronic thyroid deficiency and acute hypothyroid states.
Myxoedema coma; the injectable formulation is specifically licensed for this emergency.
Hypothyroid states arising during treatment of thyrotoxicosis.
Use alongside carbimazole to prevent subclinical hypothyroidism during thyrotoxicosis treatment.
Off-label context: specialist-led augmentation for depression.
Specialist context not listed in the selected product licences: temporary use when preparing for some thyroid-cancer or parathyroid investigations.
How does liothyronine sodium work?
Liothyronine replaces T3, the active thyroid hormone that regulates metabolism, growth and energy use in many tissues. Its effects begin within hours and decline relatively quickly after treatment stops.
liothyronine sodium preparations and strengths
Capsule
Route: Oral
Strengths: 5 micrograms, 10 micrograms, 20 micrograms
Oral solution
Route: Oral
Strengths: 10 micrograms/mL
How to take liothyronine sodium
Use the prescribed formulation exactly as directed and do not stop it abruptly without specialist advice.
Swallow tablets with water. A selected tablet may be crushed and dispersed in water when swallowing is difficult; consume all the liquid.
A selected hard capsule may be opened into water; swirl and drink the entire mixture.
Measure oral solution with the supplied oral syringe and take it with water.
The oral solution may be given through compatible feeding tubes, followed by the specified water flush.
The injection is prepared and administered by healthcare professionals.
liothyronine sodium side effects
Common or expected effects
- Reported effects, with frequency not known, include headache, tremor, sweating, heat intolerance and flushing.
- Restlessness, excitability or difficulty sleeping.
- Diarrhoea, vomiting, muscle cramps or weakness.
- Weight loss, palpitations or a fast heartbeat.
Get urgent medical advice
- Chest pain, angina, a rapid or irregular heartbeat or severe palpitations.
- An allergic reaction with rash, itching, swelling or breathing difficulty.
- Possible over-replacement over time, including atrial fibrillation, osteoporosis and fractures.
liothyronine sodium in pregnancy
Liothyronine is generally not preferred when planning pregnancy or during pregnancy because fetal development depends on an adequate maternal supply of T4. Anyone taking it who becomes pregnant or plans pregnancy should contact their endocrine or prescribing team promptly and should not stop thyroid treatment without advice, because untreated hypothyroidism also carries risks.
liothyronine sodium while breastfeeding
Small amounts of liothyronine enter breast milk. Specialist or prescriber review is appropriate because evidence is limited and treatment may affect interpretation of the baby's newborn thyroid screening; levothyroxine may be preferred.
liothyronine sodium interactions
Liothyronine can alter the effects of several medicines and some medicines can change thyroid-hormone exposure.
Warfarin and other anticoagulants
Their anticoagulant effect may increase, so clotting control may need reassessment.
Carbamazepine, phenytoin, barbiturates and primidone
They can increase thyroid-hormone metabolism; starting or stopping them may change thyroid control.
Cholestyramine and colestipol
They can reduce gastrointestinal absorption of oral liothyronine.
Common questions about liothyronine sodium
Answers are fully visible for fast scanning and source review.
Is liothyronine sodium the same as levothyroxine?
No. Liothyronine replaces T3 and acts more rapidly and briefly; levothyroxine replaces T4 and is the usual routine thyroid replacement.
Why is liothyronine sodium not routinely started for hypothyroidism?
Most people can be treated effectively with levothyroxine. NHS use of liothyronine is generally reserved for selected patients after specialist assessment.
Can liothyronine sodium be stopped suddenly?
It should not usually be stopped abruptly. Any planned withdrawal or switch should be directed by the specialist or prescriber.
Sources
These sources were used to prepare and review this medicine page.
Prepared and reviewed by the iatroX editorial team.