An overactive thyroid (hyperthyroidism) has many signs and symptoms, although it is unlikely you would develop all of them.

Symptoms of hyperthyroidism

If you have hyperthyroidism, you may experience some of the following symptoms:

• hyperactivity
• mood swings – such as anxiety, irritability and nervousness
• difficulty sleeping (insomnia)
• feeling tired all the time (fatigue)
• muscle weakness
• needing to pass stools (faeces) or urine more frequently
• excess fats in your stools – which can make them greasy and difficult to flush down the toilet (steatorrhoea)
• sensitivity to heat and excess sweating
• unexplained or unexpected weight loss – despite having an increased appetite (though in a small number of cases, the increase in appetite can lead to weight gain)
• very infrequent or light periods, or periods stopping altogether
• infertility
• loss of interest in sex 

If you have diabetes, your diabetic symptoms, such as extreme thirst and tiredness, may be made worse by hyperthyroidism.

Signs of hyperthyroidism

If you have hyperthyroidism, you may have some of the following physical signs:

• a swelling in your neck caused by an enlarged thyroid gland (goitre)
• irregular and/or unusually fast heart rate (palpitations)
• trembling or shaking (tremor)
• warm, moist skin
• redness on the palms of your hands
• loosening of your nails in their nail beds
• hives (urticaria)
• patchy hair loss (alopecia)
• twitching in your face and limbs

When to seek medical advice

See your GP if you are experiencing any of the above. They may not be the result of an overactive thyroid gland, but they will need further investigation.

It might be useful to make a list of your symptoms, as this can often be helpful in determining the correct diagnosis.