How long is whooping cough contagious?
Last updated September 3, 2026.
Whooping cough is contagious from the start of cold-like symptoms until at least 2 to 3 weeks after the coughing begins; 5 days of the right antibiotics ends contagiousness much sooner. The trap is timing: the first week or two masquerades as a cold, and that is when spread is most efficient. Antibiotics given early protect the people around you (they end transmission at 5 days) even though they barely shorten the cough once the fits start. Household exposure triggers its own rulebook: close contacts, especially infants, third-trimester pregnant women, and the immunocompromised, often get preventive antibiotics, because infant pertussis is the dangerous form. Stay home from work or school until 5 full days of antibiotics are complete, or 3 weeks from cough onset untreated. Vaccination (DTaP for kids, Tdap for adults and every pregnancy) is the prevention backbone, though vaccinated people can still catch and transmit milder cases. The cough outlasts the contagiousness by weeks to months; the "100-day cough" nickname is earned, and a lingering cough alone does not mean you are still infectious.
What to do
- Contagious window: symptom start to 2-3 weeks after cough begins.
- 5 days of antibiotics ends it: treat early to protect contacts.
- Stay home until day 5 of antibiotics done, or 3 weeks untreated.
- Exposed infants and pregnant women: call about preventive antibiotics.
- Lingering cough is normal: weeks of cough after you are no longer infectious.
Related questions
- How long does a cold last?
- How long is a cold contagious?
- What vaccines do adults need?
- When should a child see a doctor for a fever?