Indications: Adults and children for treatment of coma of myxoedema, management of severe chronic thyroid deficiency and hypothyroid states occurring in the treatment of thyrotoxicosis. Can be used also as an adjunct to carbimazole to prevent sub-clinical hypothyroidism developing during carbimazole treatment of thyrotoxicosis. May be preferred for treating severe and acute hypothyroid states but thyroxine sodium is normally the drug of choice for routine replacement therapy. Dosage and method of administration: Adults: Starting dose of 10 or 20 micrograms every 8 hours, increasing after one week, if necessary, to the usual recommended daily dose of 60 micrograms in two or three divided doses. Myxoedema Coma: 60 micrograms given by stomach tube, then 20 micrograms every 8 hours. It is more usual to start treatment with intravenous liothyronine. Adjunct to carbimazole treatment of thyrotoxicosis: 20 micrograms every 8 hours. Children below 12 years: A dose of 5 micrograms daily. Adolescents: 12 – 17 years: Initially 10-20 micrograms daily; increased to 60 micrograms daily in 2-3 divided doses. Elderly: A dose of 5 micrograms daily. For oral use only. For patients who have difficulty in swallowing a whole tablet, a whole tablet may be crushed and allowed to dissolve, with swirling, in a minimum 20 ml of water for 5 minutes. The entire volume of liquid should be consumed to ensure ingestion of the full dose. Contraindications: Hypersensitivity to the active substance or any of the excipients. Patients with angina of effort or cardiovascular diseases and thyrotoxicosis. Special warnings and precautions for use:  In severe and prolonged hypothyroidism, adrenocortical activity may be decreased. When thyroid replacement therapy is started, metabolism increases more than adrenocortical activity, this can lead to adrenocortical insufficiency requiring supplemental adrenocortical steroids. Liothyronine rather than levothyroxine would be the replacement therapy of choice during block and replace treatment of thyrotoxicosis with propylthiouracil (PTU). Treatment may result in an increase in insulin or anti-diabetic drug requirements. Care is required for patients with diabetes mellitus and diabetes insipidus. In myxoedema, care must be taken to avoid imposing excessive burden on cardiac muscle affected by prolonged severe thyroid depletion. Care is needed in the elderly who have a greater risk of occult cardiovascular disease. Baseline ECG is recommended prior to commencement of treatment to detect changes consistent with ischaemia. Patients should undergo cardiovascular monitoring, including periodic ECGs, during treatment. Liothyronine is contraindicated in established myocardial ischaemia, levothyroxine is recommended instead. Panhypopituitarism or predisposition to adrenal insufficiency (initiate corticosteroid therapy before starting liothyronine), pregnancy, breast-feeding. If metabolism increases too rapidly (causing diarrhoea, nervousness, rapid pulse, insomnia, tremors and sometimes anginal pain where there is latent myocardial ischaemia), reduce dose or withhold for 1-2 days and start again at lower dose. TSH levels should be monitored during treatment to reduce the risk of over- or under-treatment. Over-treatment risks include atrial fibrillation, osteoporosis and bone fractures. Biotin may interfere with thyroid immunoassays that are based on a biotin/streptavidin interaction, leading to either falsely decreased or falsely increased test results. The risk of interference increases with higher doses of biotin. When interpreting results of laboratory tests, consider possible biotin interference, especially if a lack of coherence with the clinical presentation is observed. For patients taking biotin-containing products, inform laboratory personnel when a thyroid function test is requested. Alternative tests not susceptible to biotin interference should be used, if available. Patients with rare hereditary problems of galactose intolerance, the total lactase deficiency or glucose-galactose malabsorption should not take this medicine. This medicine contains less than 1 mmol sodium (23 mg) per tablet, essentially ‘sodium-free’. Interactions: May potentiate the action of anticoagulants. Phenytoin levels may be increased by liothyronine. Anticonvulsants, such as carbamazepine and phenytoin enhance metabolism of thyroid hormones and may displace thyroid hormones from plasma proteins. Initiation or discontinuation of anticonvulsant therapy may alter liothyronine dose requirements. Adjustment of dosage of cardiac glycoside may be necessary if co-administered. Cholestyramine and colestipol given concurrently reduces gastrointestinal absorption of liothyronine. Liothyronine raises blood sugar levels, this may upset the stability of patients receiving antidiabetic agents. Liothyronine accelerates the response to tricyclic antidepressants. Several drugs may affect thyroid function tests: bear this in mind when monitoring patients. Co-administration of oral contraceptives may result in increased dosage requirement of liothyronine sodium. Amiodarone may result in a decreased concentration of triiodothyronine with a rise in the concentration of inactive reverse triiodothyronine. Liothyronine may enhance effects of amitriptyline and imipramine. Metabolism of thyroid hormones accelerated by barbiturates and primidone (may increase requirements for thyroid hormones in hypothyroidism). Requirements for thyroid hormones in hypothyroidism may be increased by oestrogens. Biotin may interfere with thyroid immunoassays that are based on biotin/streptavidin interaction, leading to falsely decreased or falsely increased test results. Ability to drive/use machines: No or negligible influence. Fertility, pregnancy and lactation: Safety during pregnancy is not known. Risk of foetal congenital abnormalities should be weighed against the risk to the foetus of untreated maternal hypothyroidism. Liothyronine sodium is excreted into breast milk in low concentrations. This may interfere with neonatal screening programmes. No human or animal data on the effect on fertility are available. Undesirable effects: For full list of side effects consult SmPC. Frequency unknown: Anginal pain, cardiac arrhythmias, palpitations, tachycardia, diarrhoea, vomiting, fever, flushing, heat intolerance, hypersensitivity reactions including rash, pruritus and oedema also reported, excessive loss of weight, muscle cramps, muscular weakness, headache, tremor, restlessness, excitability, insomnia, sweating, flushing. Paediatric population:  transient loss of hair. Overdose: Within a few hours of overdosage: gastric lavage or emesis. May be exaggeration of the side effects as well as agitation, confusion, irritability, hyperactivity, headache, sweating, mydriasis, tachycardia, arrhythmias, tachypnoea, pyrexia, increased bowel movements and convulsions. Treatment is symptomatic. Tachycardia in adults may be controlled with 40mg propranolol every 6 hours. MA number: PL20117/0464-0465. Cost: 15mcg (28 tablet) £152.44, 25mcg (28 tablet) £152.44. MAH: Morningside Healthcare Limited, Unit C, Harcourt Way, Leicester, LE19 1WP, United Kingdom. Legal Category: POM. Version number:  MAT-UK-LIO-0001-1 | February 2026