Individuals with ALS may have symptoms such as speech or swallowing impairment, breathing difficulties, limb stiffness, muscle weakness, twitches and cramps. They typically don’t experience significant pain, and their sensory functions, such as sight, smell and taste, will remain normal. There is usually no major impact on thinking, but up to 15–20 percent of patients with ALS have dementia. 

Because the symptoms of ALS can resemble other conditions, the disease is often misdiagnosed, and patients may go from doctor to doctor before receiving an accurate diagnosis. As the disease progresses, patients will experience significant weight loss and muscle deterioration, and require respiratory support as the condition affects the breathing muscles.