An IUD is different from the pill in several important ways. Most obviously, the pill is taken by mouth every single day, while an IUD is inserted into the uterus by a healthcare provider and lasts up to 12 years (for a copper IUD like ParaGard^®) or up to 5 years (for the hormonal IUD Mirena^®) or up to 3 years (for the hormonal IUD Skyla™). The initial cost of an IUD is much, much higher than a single pack of birth control pills, but over the long run, IUDs are usually less expensive.

 

Combined birth control pills (the most common type used) are more effective at preventing ovulation, while IUDs rely more heavily on other mechanisms of action. For example, birth control pills rely quite a bit on changing cervical mucus to alter sperm movement and on changing the lining of the uterus to prevent the implantation of a fertilized egg.

 

Overall, IUDs are quite effective, as are birth control pills when taken correctly. However, there is more room for "user error" with the pill, obviously -- for example, taking the pills incorrectly.

 

The side effects and risks also vary. Be sure to ask your healthcare provider about the specific adverse reactions and safety concerns that are most pertinent to your particular situation.