Early symptoms are usually found in specific parts of the body. They also tend to be asymmetrical, which means they only happen on one side. As the disease progresses, the symptoms generally spread to both sides of the body. Bilateral muscle weakness becomes common.

Can ALS affect one side of the body?

Although ALS affects both sides of the body, atrophy may start on one side, becoming symmetrical as the disease progresses.

What side does ALS start on?

ALS often starts in the hands, feet or limbs, and then spreads to other parts of your body. As the disease advances and nerve cells are destroyed, your muscles get weaker. This eventually affects chewing, swallowing, speaking and breathing.