Intrauterine system (IUS)

What is it? A small plastic device that works like an IUD (is put into the womb) but which also contains the hormone progestogen. It works by thickening cervical mucus to prevent sperm reaching an egg and thins the lining of the womb to prevent an egg implanting.

Advantages:
• Periods are lighter and less painful 
• Lasts for 5 years but can be taken out at any time
• Not affected by any other medicines
• Does not interfere with the spontaneity of sex 
• Normal levels of fertility will return after the IUS is removed 
• If fitted in women over 45 it can stay in place until after the menopause
  

Considerations:
• May cause irregular bleeding and may stop periods altogether 
• Small chance of infection during first few weeks after insertion 
• Possible side effects include mood changes, breast tenderness and spotty skin 
• Does not protect against sexually transmitted infections
  

Available from: Must be fitted by a medical professional and is available from your GP, local family planning clinic or specialist clinic such as Marie Stopes Reproductive Choices

Effectiveness: Over 99% effective