Whooping cough: the cough that comes in fits and lasts for months
Last updated September 3, 2026.
Whooping cough starts like an ordinary cold, then becomes coughing fits so severe they can end in vomiting, gasping, or the classic whoop. Caused by Bordetella pertussis bacteria, it is one of the most contagious respiratory infections. It is dangerous mainly for babies too young to be vaccinated; in older children and adults it is miserable and famously long-lasting (the Chinese name for it translates as the 100-day cough) but rarely dangerous.
What are the stages?
The first 1-2 weeks look like a cold: runny nose, mild cough, low fever. This is the most contagious phase, and nobody suspects pertussis yet. Then the paroxysmal phase: bursts of rapid, uncontrollable coughs (5-10 or more in one breath) followed by a desperate in-breath that produces the whoop in children, then often vomiting or exhaustion. Babies under 6 months may not whoop at all; instead they pause breathing (apnea), turn blue, or struggle to feed. Fits are worst at night. The cough then fades over weeks to months, though a later ordinary cold can briefly bring the fits back. Adults often just have a stubborn cough lasting over 3 weeks, sometimes with a rib-cracking intensity.
Why the danger concentrates in young babies
About half of babies under 12 months who catch pertussis need hospital care, and the deaths occur almost entirely in infants under 3 months: apnea, pneumonia, seizures, and brain injury from oxygen deprivation are the mechanisms. This is why vaccination strategy targets the people around the baby: a Tdap booster in every pregnancy (passing antibodies through the placenta), plus up-to-date boosters for parents, grandparents, and caregivers. Immunity from vaccination or infection fades over years, so previously vaccinated teens and adults are the usual transmission source.
What actually helps?
- Antibiotics, early: a macrolide such as azithromycin (typically 5 days) reduces spread and shortens illness, but only if started in the first 1-2 weeks, before the fits begin. Started later, antibiotics still stop transmission but do not shorten the cough, because the cough is driven by toxin damage already done.
- Protect the contacts: close contacts of a confirmed case, especially households with a baby or pregnant woman, are offered preventive antibiotics regardless of symptoms.
- Small, frequent feeds for babies: reduces vomiting after fits. Feed after coughing fits, not before.
- Comfort during fits: sit upright, stay calm, sip water between fits. Cough syrups and suppressants do not work for pertussis and are not recommended in young children.
- Stay home: contagious until 5 days of effective antibiotics are completed, or 3 weeks from the start of fits without antibiotics.
When is it an emergency?
In a baby under 6 months: any pause in breathing, blue or gray color around the lips, a coughing fit ending in limpness or unresponsiveness, poor feeding with fewer wet diapers, or seizures. Call emergency services for apnea or blue spells. Older children and adults need urgent care for breathlessness between fits, chest pain, fainting during fits, or coughing up blood. Any baby under 6 months with a suspected whooping cough cough should be assessed the same day even if currently well. Pymander's escalation routing is built and tested specifically for this class of decision; see the safety architecture working paper.
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Common questions
My child is vaccinated. Can they still get whooping cough?
Yes, but usually milder. Pertussis vaccines are good but imperfect, and protection fades over 5-10 years, so vaccinated children and adults can still catch it. Their illness tends to be shorter and less severe: a stubborn cough rather than dramatic fits. Vaccination still matters enormously, because its main job is protecting young babies too small for their own shots, and it reduces both catching and spreading the infection.
How long does whooping cough last?
Plan for months, not weeks. The cold-like phase lasts 1-2 weeks, the severe coughing-fit phase typically runs 2-8 weeks, and the fading convalescent phase can stretch another few weeks to months. Total duration of 6-12 weeks is common, and a later unrelated cold can temporarily retrigger the fits. A cough persisting past 3 months with normal energy and no fever is usually still the tail of pertussis, but deserves one check to exclude other causes.
Are antibiotics worth taking if the cough has been going for weeks?
For stopping the cough, no: by the paroxysmal phase, the bacteria's toxin has already damaged the airway lining, and the cough continues until it heals, antibiotics or not. Antibiotics are still given for one reason: to stop you infecting others, especially before contact with babies or pregnant women. They genuinely change the illness only if started in the first 1-2 weeks, when it still looks like a cold, which is the tragic irony of pertussis timing.
When can my child go back to school?
The standard rule: after completing 5 days of an effective antibiotic, or 21 days after the coughing fits started if no antibiotics were given. Before that point they are contagious and should stay home. After it, they can return even while still coughing, since the lingering cough is not infectious. Schools and nurseries sometimes ask for a doctor's note; your clinician can provide one once the exclusion window has passed.
What is the pregnancy vaccination advice?
A Tdap (or equivalent pertussis-containing) booster is recommended during every pregnancy, ideally between 27 and 36 weeks. The mother makes antibodies that cross the placenta and protect the baby in the first 2-3 months of life, before the baby's own vaccinations start working, which is exactly the window where pertussis kills. Partners, grandparents, and regular caregivers should also be up to date; this cocooning strategy is the main defense newborns have.
How is whooping cough diagnosed?
In the first 2-3 weeks, a nasopharyngeal swab tested by PCR is the standard and most sensitive method. Later in the illness, when bacteria are gone but the cough continues, blood tests for pertussis antibodies can confirm a case that has been going for weeks. In practice, clinicians often treat on the strength of the story alone (fits, vomiting after cough, known exposure) because waiting for confirmation delays protection of contacts.
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