Causes

The exact cause of Guillain-Barre syndrome isn't known. The disorder usually appears days or weeks after a respiratory or digestive tract infection. Rarely, recent surgery or vaccination can trigger Guillain-Barre syndrome. Recently, there have been cases reported following infection with the Zika virus. Guillain-Barre syndrome may occur after infection with the COVID-19 virus. It's also a rare reaction in those who receive the Johnson & Johnson COVID-19 vaccine.

In Guillain-Barre syndrome, your immune system — which usually attacks only invading organisms — begins attacking the nerves. In AIDP, the most common form of Guillain-Barre syndrome in the U.S., the nerves' protective covering (myelin sheath) is damaged. The damage prevents nerves from transmitting signals to your brain, causing weakness, numbness or paralysis.