Certain types of hormonal birth control implants have been associated with dozens of cases of Idiopathic Intracranial Hypertension (IIH), a brain injury that occurs when high levels of cerebrospinal fluid increase pressure inside the skull. In severe cases, blindness can occur unless the fluid is drained surgically.
What is Nexplanon?
Nexplanon is a matchstick-sized birth control implant that is manufactured by Merck & Co. Once placed under the skin, it prevents pregnancy for up to three years by slowly releasing the hormone etonogestrel. Nexplanon is the newer version of Implanon.
Nexplanon and Idiopathic Intracranial Hypertension (IIH)
No one knows if Nexplanon causes IIH. The term “idiopathic” means “unknown cause.” The condition is rare, but many risk-factors have been identified. One of the first studies to link birth control and IIH was published in the New England Journal of Medicine in 1995. Researchers reported 56 cases of IIH with optic edema in young women (average age 22) who were using a birth control implant containing levonorgestrel. More recent case reports have linked IIH with progestin-only injections and exogenous estrogen in birth control.
In 2012, the British Medical Journal published a study linking the use of subcutaneous birth control implants with a 40% increased risk of blood clots. In rare cases, arterial blood clots that travel to the brain can cause “secondary intracranial hypertension.” This condition occurs when pressure inside the skull increases due to a blood clot physically obstructing the flow of cerebrospinal fluid. Click here to read more.
In clinical trials, headaches were reported by 25% of women on Nexplanon. Headaches are also a symptom reported by over 90% of people with IIH. However, it is not clear that these conditions are related. Women on Nexplanon who develop severe headaches should be evaluated by a doctor and discontinue Nexplanon if necessary.
IIH can put pressure on the optic nerve (transmits signals between the brain and eyes) and the optic disc (located in the “blind spot” at the back of the eye). This can lead to numerous complications. One complication, papilledema, occurs when the optic disc becomes swollen. Symptoms may include double-vision, blurry vision, and temporary loss of vision lasting 30 seconds. Over time, IIH can damage the optic nerve and cause permanent blindness. About 5% of people with IIH develop blindness.