What is the first treatment tried for hypothyroidism?

An underactive thyroid does not make enough thyroid hormone for the body's needs. This can contribute to tiredness, feeling cold, dry skin, constipation, low mood and difficulty concentrating, although symptoms vary and can overlap with other conditions.

Thyroid hormone replacement supplies a form of hormone the body can use. The starting amount is individual, and treatment is adjusted using symptoms and a Thyroid Function Test rather than by symptoms alone. Improvement may be gradual, so keep follow-up appointments even if you feel better.

Take the medicine consistently as directed, usually at the same time each day. Ask how to separate it from supplements or other medicines that can affect absorption, and tell your clinician about pregnancy, heart disease and any new medicines. Do not change the dose or stop treatment without advice.

A [Thyroid Function Test](/treatments/diagnostics-and-screening/thyroid-function-test/) helps guide adjustments. A [Chronic Disease Review](/treatments/consultations-and-assessment/chronic-disease-review/) can review symptoms, medicines and follow-up. Read more about [Thyroid Hormone Replacement](/treatments/medical-management/thyroid-hormone-replacement/) and [Hypothyroidism](/conditions/hypothyroidism/).

Seek urgent help for severe drowsiness, confusion, unusually slow breathing, fainting, chest pain or a very fast or irregular heartbeat. Contact your clinician if symptoms worsen after a dose change, you develop troublesome palpitations or tremor, or you are pregnant or planning pregnancy.

How will my dose be chosen? When should I repeat blood tests? How should I take the medicine around breakfast and supplements? Which symptoms suggest the dose is too high or too low?