Smallpox is fatal in 30% of cases. Early symptoms include high fever and fatigue. Later, the virus causes a characteristic rash, especially on the face, arms, and legs. The spots become filled with clear fluid, turn to pus, and then form a crust, which eventually dries and falls off.

The first line of treatment is usually a smallpox vaccine given within 3–4 days of exposure to the smallpox virus. Vaccination can make the disease less severe or may help prevent it. After that, treatment focuses on relieving symptoms and rehydration.

Smallpox is one of the most dangerous infectious diseases in humans. It can cause dangerous complications for the patient's health, and can even lead to death if not treated promptly. Currently, we still have no specific treatment for this disease, but smallpox is completely preventable through vaccination.