Greater Glasgow and Clyde Medicines

Liothyronine in combination with levothyroxine for hypothyroidism

Key messages

  • A new NHSGGC guideline (on StaffNet) advising on the place in therapy of liothyronine (T3) as an add-on therapy in combination with levothyroxine (T4) in the treatment of hypothyroidism in adults has now been published.
  • Liothyronine tablets are now included in the NHSGGC Adult Formulary restricted to specialist initiation on the advice of a consultant endocrinologist in accordance with the guideline. Use of oral liothyronine for other indications remains non-formulary.
  • Licensed 5microgram, 10microgram and 20microgram tablets of liothyronine are now available in the UK. NHSGGC does not support the use of unlicensed liothyronine products and thyroid extracts as the safety, quality and efficacy of these products cannot be assured.


Levothyroxine replacement therapy (T4) is the standard treatment of hypothyroidism and results in normalisation of biochemistry and symptoms in the vast majority of patients. It is included in the NHSGGC Adult Formulary as the preferred treatment of hypothyroidism in adults.

In very rare situations, patients experience continuing symptoms of hypothyroidism severe enough to have a material impact on day to day functioning despite treatment with levothyroxine and adequate biochemical correction. Where the patient has continuing symptoms not explained by another diagnosis after full evaluation and, if necessary, a retrospective review of the original diagnosis of hypothyroidism, then a trial of T3 may be considered in accordance with the new guideline (on StaffNet).

The decision to prescribe a trial of combination T3/T4 should be reached following an open and balanced discussion between an endocrinologist and the patient. This should include an explanation of the uncertain benefits, likely risks of over-replacement, lack of long-term safety data and the possibility of not continuing if the trial shows no benefit.

The decision to continue treatment should be based on review by an endocrinologist after at least 3 months of stable dosing.

Patients benefitting from treatment may be discharged to the care of their GP, once stabilised for ongoing treatment and monitoring, on the understanding that advice may be sought from an endocrine specialist on any aspect of patient care which is of concern.

Treatment changes are to be under consultant NHS endocrinologist review or in circumstances where a GP is fully supported by a consultant NHS endocrinologist.


Published 23/12/2020. Medicines Update blogs are correct at the time of publication.