Cases of Benign Intracranial Hypertension (BIH) have been reported in women who were implanted with Implanon, a popular contraceptive. BIH is a rare neurological disease that can cause chronic headaches, migraines, vision loss, or blindness.
What is Implanon?
Merck & Co. manufactures Implanon, a matchstick-sized contraceptive implant that is inserted under the skin on a woman’s arm. It prevents pregnancy for up to three years by slowly releasing etonogestrel, a synthetic version of the hormone progestin. Implanon was approved by the FDA in 2006.
What is the problem?
There are no studies proving that Implanon causes BIH. However, there are a growing number of case reports linking certain types of hormonal birth control with this side effect.
For example, the New England Journal of Medicine published a study in 1995 linking 56 cases to Norplanon, a birth control implant that is very similar to Implanon. The difference is that Norplanon contains levonogestrel.
Bayer, the manufacturer of Mirena, is facing lawsuits for failing to warn about the risk of BIH. Women in the litigation accuse Bayer of downplaying risk information, which could delay diagnosis and increase the risk of complications.
Implanon and Headaches
Up to 25% of women on Implanon suffer from headaches, according to data from clinical trials. Headaches are one of the most common side effects of hormonal contraceptives, and they are also the most common sign of BIH. It is not clear that the conditions are related, but drug-makers recommend that women who have severe migraines or persistent headaches should be evaluated by a doctor.
Benign Intracranial Hypertension
Benign Intracranial Hypertension (BIH) is a neurological syndrome that is currently known as Idiopathic Intracranial Hypertension (IIH). It causes cerebrospinal fluid levels to increase inside the skull. This results in higher pressure on the brain, which can cause headaches. It can also damage the optic nerve and cause vision problems or blindness.
- Migraines that become progressively more frequent
- Double-vision (diplopia)
- Blurry vision
- Loss of visual field
- Enlargement of the blind spot
- Papilledema (swelling of the optic disc)
- Sensitivity to light (photophobia)
- Ringing in the ears (tinnitus)
- And more