The 4 stages of dengue fever are: 1. Febrile phase: The onset of dengue is characterized by high fever, severe headache, joint and muscle pain, and rash. 2. Critical phase: Some individuals progress to a critical phase, which typically occurs around the time the fever subsides. This phase is marked by plasma leakage, bleeding, organ impairment, and can be life-threatening. 3. Recovery phase: After the critical phase, the individual begins to recover, and symptoms gradually subside. 4. Convalescent phase: During this phase, the person may experience weakness, fatigue, and loss of appetite as the body recovers. It is important to monitor symptoms and seek medical attention if necessary.