Whooping Cough in Babies and Kids: Symptoms and Why It Is Dangerous

Whooping cough (pertussis) is a bacterial infection that begins like a cold and can progress to severe coughing fits that last for weeks. In babies it can look different: there may be little coughing and no "whoop," but pauses in breathing or a blue color around the lips. Young infants are at the highest risk of serious illness. This article covers symptoms, complications, diagnosis, treatment, prevention and when to get urgent care.

Whooping cough in babies and kids: what it is and how it spreads

Whooping cough, also called pertussis, is an infection of the airways caused by a bacterium called Bordetella pertussis. MedlinePlus (NIH) describes it as a very contagious respiratory illness. It spreads through tiny droplets when an infected person coughs or sneezes, and it can pass easily among people who share a home.

The bacteria irritate the lining of the airways and can trigger repeated bouts of forceful coughing. The cough can linger for weeks, which is why the illness has earned the nickname "the 100 day cough." Many babies catch it from someone close to them, such as a parent, sibling or caregiver. Those people may have only a mild cough and may not know they have pertussis.

If your child's cough sounds more like barking or a tight, noisy breath, that may be a different illness. Our article on croup and other childhood coughs covers that comparison. The rest of this page focuses on pertussis.

Whooping cough symptoms by stage

Pertussis is often described in stages. Not every child follows the pattern neatly, and the stages blur together, but the outline can help you recognize what is happening.

Early stage: it looks like a cold

The first symptoms often include a runny nose, mild cough, sneezing and sometimes a low fever. At this point it is very hard to tell pertussis from an ordinary cold. This is also a stage when the infection can spread easily, because nobody suspects it.

Coughing-fit stage

After the early stage, the cough can become more severe. Typical features include:

• Rapid series of coughs in a single breath, one after another.
• A high-pitched "whoop" sound when the child finally breathes in. Many children, especially infants and some teens, do not make this sound.
• Vomiting after a coughing fit.
• A red or purple face during the fit, and exhaustion afterward.
• Seeming fairly well between fits.

Fits may be more frequent at night. Feeding, crying or being startled can set one off.

Recovery stage

The cough slowly becomes less frequent and less intense, but it can last for weeks. A later cold or other respiratory infection can bring the coughing back for a while even after the pertussis infection has cleared.

Why whooping cough is more dangerous for babies

Young infants have small airways and have not completed their vaccine series. A bout of coughing that would exhaust an older child can interfere with a baby's ability to breathe.

In babies, pertussis often does not look like the classic "whooping" illness. Instead you may see:

• Pauses in breathing (apnea): the baby stops breathing for a stretch of time, sometimes without much coughing at all.
• Color change: lips, tongue or face turning blue or gray during or after a fit.
• Gagging or gasping instead of a clear whoop.
• Trouble feeding: coughing fits during feeds, or vomiting afterward, so the baby takes in less milk or formula.

Because of these risks, young infants, especially those under 3 months, are often admitted to hospital so that breathing, oxygen levels and feeding can be monitored. Our article on when to worry about a baby's breathing explains what concerning breathing looks like in more detail.

Complications of pertussis

Most older children recover, but complications can occur, and they are more likely in infants. A review of pertussis in PubMed Central describes the illness and its potential complications. Possible problems include:

• Pneumonia: a lung infection, which can be caused by the pertussis bacteria or by another germ taking advantage of irritated airways.
• Breathing pauses and low oxygen: particularly in young babies.
• Seizures: which may be related to low oxygen or other effects of severe illness.
• Dehydration and weight loss: when vomiting and coughing interfere with feeding.
• Injuries from forceful coughing: such as nosebleeds, small bleeds in the whites of the eyes, or hernias. In rare cases, severe coughing has been linked to rib fracture or collapsed lung. A published case report describes one such example, in an older patient.

Complications do not occur in every case, and the outlook depends on age, vaccination status, other health conditions and how early the infection is recognized.

How whooping cough is diagnosed

Clinicians combine the history of the cough, a physical exam and testing. Because early pertussis resembles a cold, the diagnosis is often considered when a cough lasts, comes in fits, or when a child has been around someone with the infection.

Testing commonly involves a swab of the nose and throat area that is checked for the bacteria's genetic material or grown in a lab. Blood tests that look for antibodies may be used in some situations, but they are interpreted differently depending on vaccination history and timing. Research on newer testing methods, including CRISPR-based approaches, is ongoing. A chest X-ray may be done if pneumonia is a concern.

A clinician may start treatment before results return if suspicion is high, particularly in a young baby.

Treatment and what to do at home

MedlinePlus (NIH) notes that antibiotics are used to treat whooping cough, and macrolides such as azithromycin are commonly chosen. Started early, they may reduce how long the person is contagious and may lessen illness. They may not shorten the cough much once the coughing-fit stage is underway. Young babies need specialist guidance on which antibiotic is used, because some macrolides, including azithromycin and erythromycin, have been linked to a small risk of a stomach outlet problem (infantile hypertrophic pyloric stenosis) in very young infants. A baby younger than about 6 weeks (especially under 2 weeks) who takes a macrolide should be watched for forceful or projectile vomiting after feeds, poor feeding or poor weight gain. Call the prescriber right away if you see any of these. Your prescriber chooses the drug and the dose for your child's age and weight, so follow the label and their instructions, and ask the pharmacist if anything is unclear. Do not skip, stop or change doses on your own.

Supportive care matters too, and a clinician can tailor it to your child:

• Offer smaller, more frequent feeds and fluids, since large feeds may bring on vomiting.
• Keep the child upright or supervised during and after coughing fits.
• Keep the air free of smoke and other irritants.
• Do not give over-the-counter cough or cold medicines to infants or young children. They have not been shown to help pertussis and can be harmful, and labels carry age cautions. Ask your pediatrician or pharmacist if you are unsure.

Babies with breathing pauses, color changes or poor feeding often need hospital care, where oxygen, fluids and monitoring can be provided.

Protecting babies and kids: vaccines and close contacts

Vaccination is the main way to lower the risk of serious pertussis. The routine childhood vaccine series includes a pertussis-containing vaccine given in several doses beginning in infancy, with later boosters. MedlinePlus (NIH) lists childhood vaccines, and our article on why vaccines follow a set schedule explains why timing matters. Your pediatrician can give you the exact schedule for your child and help you catch up if doses were missed.

Protection can fade over time, so older children, teens and adults are also offered a booster. MedlinePlus (NIH) describes the Tdap vaccine, which combines tetanus, diphtheria and pertussis protection. Pregnant people are commonly advised to receive a Tdap dose during each pregnancy so that some antibodies pass to the baby. Ask your obstetric clinician about timing.

Vaccines do not provide complete protection, and a vaccinated child can still catch pertussis, though the illness is often milder. Other protective steps include:

• Keeping a newborn away from anyone with a cough, where possible.
• Making sure people who care for the baby are up to date on their own pertussis vaccine.
• Washing hands and covering coughs.
• Telling your clinician about any exposure or diagnosis in the home. Clinicians may recommend preventive antibiotics for close contacts at higher risk, particularly where a young infant lives.
• Keeping a child with confirmed pertussis home from child care or school until your clinician says it is appropriate.

Older children, teens and the rest of the family

School-age children and teens often have a milder illness: a cough that lasts for weeks, sometimes with fits and vomiting, but without much else. Because it can be mistaken for bronchitis, an asthma flare or a lingering cold, it may spread unnoticed. A clinician may consider pertussis if a cough keeps going for weeks or if there is a known exposure. For general causes of a long-lasting cough, see causes of persistent cough and the MedlinePlus (NIH) cough page.

When to seek medical care

Call 911 if your baby or child stops breathing, turns blue or gray, becomes limp or very hard to wake, has a seizure, or struggles hard to breathe. Those problems can progress quickly and need emergency care.

Go to the emergency room now if a baby under 3 months has a suspected pertussis cough, or if a baby of any age cannot keep down feeds or fluids. Young infants can have breathing pauses with little coughing, so they should not wait for a routine appointment.

For a baby of 3 to 6 months with a cough that comes in fits or with gagging, arrange to be seen in person today, in the emergency room if the pediatrician cannot see the baby right away. For an older child, contact your pediatrician the same day if your child cannot keep down feeds or fluids, shows signs of dehydration, or has been near someone diagnosed with pertussis. A cough that keeps going for weeks, or that comes in fits with vomiting afterward, also deserves a medical visit.

When to Seek Medical Care