ASMs and birth control (contraception)

Some ASMs (those that are ‘enzyme-inducing’) can make certain forms of birth control (including the morning after pill) less effective and increase the risk of an unplanned pregnancy. Enzyme inducing ASMs include:

The impact of taking hormonal contraception varies among women. Some women find that hormonal birth control increases seizure activity, whereas for others it decreases seizures or has no impact at all.

So, if you are considering contraception or already using contraception it’s a good idea to chat with your doctor about which method is right for you and why. 

You may also want to visit the NPS Medicinewise website for further information about medications.

Contraception that can be affected by ASMs

A number of hormonal contraceptive methods can become less reliable when taking certain ASM’s and increase your risk of an unplanned pregnancy.

These include:

  • Combined oral contraceptive pill (‘the pill’). ‘The pill’ contains oestrogen and progesterone hormones and works by preventing the ovaries from releasing an egg each month. Some ASMs make the pill less effective. It may be recommended that a higher dose of the pill is taken, or an alternative birth control method used instead.
  • Progesterone-only pill (‘mini pill’). The ‘mini pill’ contains the hormone progesterone and considered less effective than the combined pill. It not recommended as birth control if you are taking certain ASMs.
  • Emergency contraceptive pill (‘the morning after pill’). The ‘morning after pill’ is a form of emergency contraception that can be taken within the first 72 hours after sex. Some ASMs can reduce its effectiveness, so it is a good idea to discuss the ASMs you are taking with the pharmacist if you are accessing the ‘morning after pill’.
  • Contraceptive implant. These implants contain progesterone and are implanted under the skin in the arm. The contraceptive effectiveness of implants may be affected some ASMs.
  • Vaginal Ring. This soft plastic ring contains the hormones oestrogen and progesterone. Like the combined oral contraceptive pill it works to prevent the ovaries from releasing an egg each month. This may not be an effective method of birth control if taking certain ASMs.
  • Natural contraception (‘rhythm method’). Natural contraception means working out which times in your menstrual cycle are ‘safer’ times to have sex. This method can be affected by hormonal changes in the body and it can be unpredictable. Because of this it is not recommended if you are taking ASMs.

It is important to remember that hormonal contraceptive methods do not give protection from sexually transmitted diseases (STIs). For more information about this visit Family Planning Victoria.

Contraception methods not affected by ASMs

  • Condoms
  • Diaphragms
  • Contraceptive injections (such as Depo Provera). Women with epilepsy often have an injection every 10 weeks.
  • Intra-uterine devices such as a Mirena IUD.

Lamotrigine (Lamictal) and contraception

Some oral contraceptives can affect how well ASMs work. Some studies have shown that oral contraceptives affect how much lamotrigine (Lamictal) stays in your blood. If you are taking this medication, other forms of contraception such as condoms, diaphragms, contraception injections or Intra-uterine devices may be more suitable for you.   

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