Treatment for an underactive thyroid involves taking daily hormone replacement tablets, called levothyroxine, to raise your thyroxine levels.
You'll initially have regular blood tests until the correct dose of levothyroxine is reached. This can take a little while to get right.
Once you're taking the correct dose, you'll usually have a blood test once a year to monitor your hormone levels.
You'll usually need treatment for the rest of your life. However, with proper treatment, you should be able to lead a normal, healthy life.
If an underactive thyroid is not treated, it can lead to complications, including heart disease, goitre, pregnancy problems and a life-threatening condition called myxoedema coma (although this is very rare).