Myasthenia gravis (MG) is an autoimmune condition that can cause muscle weakness. Normally, the body makes antibodies to attack viruses or bacteria that enter the body. In people with MG, antibodies attack receptors that allow your body to communicate with your muscles and tell them to move. These antibody attacks cause muscle weakness.
MG often causes muscle weakness in the following areas:
- muscles that control chewing and swallowing
- arms and legs
- muscles that control breathing