Hyperthyroidism and hypothyroidism at the same time

An overactive thyroid can cause heat intolerance, sweating, anxiety, diarrhoea, and palpitations, while an underactive thyroid can cause tiredness, feeling cold, constipation, and dry skin. Symptoms may overlap, change over time, or reflect medicine dosing rather than two separate conditions operating at once. Autoimmune thyroid disease can also alter thyroid function over time. Because symptoms cannot measure hormone levels reliably, clinicians use blood tests and your treatment history to determine whether thyroid activity is high, low, or currently in range.

Book a review if symptoms alternate, return after a dose change, or make daily activities difficult. Bring the names and doses of thyroid medicines, the timing of each dose, and any supplements. Your clinician may repeat thyroid blood tests and adjust treatment gradually. Do not alternate doses or stop medicine on your own. Related information is available under [Hyperthyroidism](/conditions/hyperthyroidism/), [Feeling Anxious](/symptoms/feeling-anxious/), and [Difficulty Sleeping](/symptoms/difficulty-sleeping/).

Seek emergency care for chest pain, fainting, severe breathlessness, confusion, or a very fast or irregular heartbeat. Contact your clinician promptly for marked weakness, repeated vomiting, severe agitation, or rapidly worsening symptoms after a thyroid medicine change. These signs need assessment rather than guessing whether thyroid activity is high or low.

Do my symptoms fit high thyroid activity, low activity, medicine effects, or another problem? Which tests should be repeated and when? How should I take my medicine around food and supplements? What should I do if symptoms change suddenly?