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pediatric-illness

Whooping Cough (Pertussis): What Parents Need to Know

Pertussis causes prolonged severe coughing in older children; in babies it causes dangerous pauses in breathing and can be fatal. Very contagious. Young infants need emergency care immediately.

Three stages of whooping cough

Pertussis typically moves through three stages, though young infants may not follow this pattern 1:

1. Catarrhal stage (1–2 weeks): Begins like a mild cold — runny nose, mild cough, low-grade fever. This is the most contagious period, before anyone suspects pertussis. 2. Paroxysmal stage (1–6 weeks or longer): The characteristic violent, rapid coughing fits begin. A child may cough repeatedly without being able to take a breath, ending in a high-pitched 'whoop' as they gasp for air. Coughing attacks can peak at roughly 15 episodes per day. Between fits, the child can appear relatively well. 3. Convalescent stage: Coughing gradually improves over weeks to months. Pertussis is sometimes called the '100-day cough' because it can linger so long 2.

Why pertussis is most dangerous in young infants

Infants under 6 months — and especially those under 2 months — who have not yet completed their primary vaccine series face the greatest danger 1. Rather than the classic whoop, these babies may simply stop breathing (apnea) or turn blue (cyanosis) during a coughing spell, or may have brief pauses in breathing without dramatic coughing at all 2.

In infants, apnea may be the only symptom, with the cough minimal or absent 2. The most common complications in this group are breathing cessation (reported in about 68% of infant hospitalizations) and pneumonia (about 22%). Approximately one-third of infants under 12 months with pertussis require hospitalization. Virtually all pertussis deaths occur in infants under 3 months 1.

How pertussis spreads — and why cocooning matters

Pertussis spreads through respiratory droplets from coughing or sneezing and is highly contagious, particularly during the catarrhal stage 1. Many babies who get whooping cough are infected by older siblings, parents, or caregivers who do not know they have it — because pertussis in older children, teens, and adults can look like a prolonged mild cough 1.

This is why vaccination recommendations include Tdap for adolescents and adults who will be in close contact with a new baby (sometimes called 'cocooning'). The CDC recommends that pregnant people receive Tdap during each pregnancy to pass some immunity to the newborn before birth 1.

Treatment and antibiotic use

Pertussis is bacterial and is treated with antibiotics — most effective when started in the first one to two weeks before severe coughing begins 2. Treatment started later in the course may not significantly shorten the illness but is still given to reduce spread.

Household and close contacts of a confirmed pertussis case are typically offered preventive (prophylactic) antibiotics regardless of vaccination status, particularly if there is an infant in the household 2. Vaccinated children and adults can still develop pertussis, often with milder illness, because protection from acellular pertussis vaccines wanes over time.

What to watch for at home

A young child recovering from pertussis at home (if deemed stable enough) needs careful observation. Coughing fits can be triggered by feeding, crying, or activity 2. Keeping the child calm, feeding in small amounts, and noting the duration, frequency, and color of the child during and after coughing fits helps the care team make informed decisions. Any sign of breathing difficulty, bluish color, or prolonged difficulty recovering after a coughing spell is a reason to seek emergency care without delay.

Common questions

My baby has a bad cough but no 'whoop' — could it still be pertussis?

Yes. Young infants often do not produce the classic whooping sound. Instead they may cough, gag, turn red or blue, or have brief pauses in breathing. Any infant under 6 months with a significant or worsening cough should be evaluated promptly.

My older child is vaccinated — are they protected from pertussis?

Vaccination significantly reduces risk, but protection from pertussis vaccines wanes over time — particularly the acellular vaccines used today. Vaccinated children and adults can still develop pertussis, often with milder illness. Tdap booster shots help extend protection.

How long is a child with pertussis contagious?

Without treatment, a child with pertussis is contagious from the start of cold-like symptoms through roughly three weeks of coughing. With appropriate antibiotics started early, the contagious period is typically reduced to five days from the start of treatment.

We were exposed to someone with whooping cough — what should we do?

Contact your child's (and your own) healthcare provider promptly to discuss whether preventive antibiotics are recommended, particularly if there is an infant in the household. Do not wait for symptoms to develop.

When to get care right away

  • —Any infant under 6 months with a significant, worsening, or prolonged cough — do not wait
  • —Baby or child who turns blue, purple, or very pale during or after a coughing spell
  • —Baby who stops breathing, even briefly, during or after coughing
  • —A coughing spell that lasts more than 1 minute without the child recovering well
  • —Child appears limp or unusually unresponsive after a coughing fit
  • —Fast or labored breathing, retractions (skin pulling in between ribs), or nasal flaring at rest
  • —Signs of dehydration: no wet diapers, no tears, very dry mouth
  • —Seizure during or after illness

An infant who turns blue, stops breathing, or cannot recover after a coughing fit: call 911 immediately. Any infant under 3 months with a worsening cough or breathing difficulty should be taken to the emergency department without delay.

This article is general health information for parents. Pertussis in young infants is a medical emergency. Do not use this article to self-manage suspected pertussis in a baby — contact a healthcare provider or emergency services right away.

References

  1. 1.Centers for Disease Control and Prevention (2025). About Whooping Cough (Pertussis). CDC — Pertussis (Whooping Cough). link ✓Transmission through respiratory droplets, greatest risk in babies under 1 year, infant-to-infant spread from unrecognized adult cases, Tdap in pregnancy, and vaccination recommendations
  2. 2.Centers for Disease Control and Prevention (2025). Clinical Features of Pertussis. CDC — Pertussis (Whooping Cough) — Healthcare Provider Resources. link ✓Three-stage clinical progression; apnea as sole infant symptom; complication rates (apnea 68%, pneumonia 22%); treatment window of first 1–2 weeks for maximum efficacy; prophylaxis for household contacts

2 sources, numbered by first appearance. General health information, not medical advice — synthetic demonstration content.