The average time from infection to appearance of signs and symptoms (incubation period) is 10 days. The incubation period can range from 3 to 21 days. The most common type of tetanus is called generalized tetanus. Signs and symptoms begin gradually and then progressively worsen over two weeks. They usually start at the jaw and progress downward on the body. Signs and symptoms of generalized tetanus include: Painful muscle spasms and stiff, immovable muscles (muscle rigidity) in your jaw Tension of muscles around your lips, sometimes producing a persistent grin Painful spasms and rigidity in your neck muscles Difficulty swallowing Rigid abdominal muscles