The main symptom of thyroid cancer is a lump in the front of the neck.
But thyroid cancer tends to develop slowly and there may not be any symptoms at first.
Thyroid cancer often causes a painless lump or swelling low down in the front of the neck.
However, neck lumps are common and are usually caused by a less serious condition, such as an enlarged thyroid (goitre). Only around 1 in every 20 neck lumps are cancer.
A neck lump is more likely to be cancer if it:
See a GP if you have a swelling or lump at the front of your neck. While it's unlikely to be cancer, it's important to get it checked.
Other symptoms of thyroid cancer include:
Rarely, thyroid cancer can affect the production of thyroid hormones and cause diarrhoea and flushing.
These symptoms can be caused by other conditions, but it's a good idea to see a GP if you develop any persistent symptoms that you're worried about.
Page last reviewed: Sun Aug 2022 Next review due: Wed Feb 2020