How long should I self-isolate after the onset of a measles rash?

Measles Isolation Duration

Individuals with measles should self-isolate for at least 4 days after the onset of the rash to prevent transmission to others. 1, 2

Infectious Period

• Measles is contagious from 4 days before rash onset through 4 days after rash onset, making early transmission possible before diagnosis. 1, 2
• This extended pre-rash infectious period (4 days before symptoms are obvious) is why measles spreads so rapidly and why isolation must continue for the full duration after rash appears. 1, 2

Standard Isolation Protocol

• Isolate for a minimum of 4 days after the rash first appears. 1, 2, 3
• During any healthcare visits, immediately wear a medical mask and request placement in a negative air-pressure isolation room if available. 2, 3
• If no isolation room exists, stay in a private room with the door closed. 2

Special Circumstances Requiring Extended Isolation

Healthcare Workers

• Healthcare workers with measles must be excluded from work until at least 4 days following rash onset. 1, 2
• This is non-negotiable due to the high-risk environment and vulnerable patient populations. 1

Immunocompromised Patients

• Immunocompromised individuals may require longer isolation periods as they can shed virus for extended durations. 3
• These patients should have received immune globulin (0.5 mL/kg, maximum 15 mL) if exposed, regardless of vaccination status. 3

Critical Pitfalls to Avoid

• Do not end isolation early: The full 4-day period after rash onset must be completed, as viral shedding continues throughout this time. 2, 3
• Do not underestimate pre-rash contagiousness: You were already infectious for 4 days before the rash appeared, which is why contacts need evaluation and potential exclusion. 1, 2
• Do not use regular surgical masks: N95 respirators or equivalent are required for anyone entering the room of a measles patient, as measles is airborne. 2, 3
• Do not allow unvaccinated household members or contacts to remain exposed: Susceptible contacts should receive post-exposure prophylaxis with MMR vaccine (within 72 hours) or immune globulin (within 6 days). 2

Contact Management

• Exposed individuals without immunity who did not receive post-exposure vaccination should be excluded from public settings from day 5 through day 21 after exposure. 1, 2
• If immune globulin was administered to an exposed person, observation should extend to 28 days after exposure. 2