Pertussis (whooping cough)

Pertussis, also known as whooping cough, is a sudden-onset bacterial infection of the lungs and upper respiratory tract.

Pertussis can be a very serious illness in babies because their airways are small. Babies under three months or older babies with difficulty breathing, eating or drinking may need to be admitted to hospital to support their breathing and nutrition.

Signs and symptoms of pertussis

Common symptoms include:

  • persistent, severe coughing that occurs in clusters 
  • a cough followed by vomiting of milk, food or mucus
  • a change in the colour of the face when coughing
  • a high-pitched whoop sound when breathing in.

Symptoms start seven to 14 days after a child is exposed to the infection. 

How pertussis is diagnosed

If the doctor thinks your child has pertussis, they will take a swab of the secretions (mucus) from your child's nose for testing. It may take five to seven days for your doctor to get the results. 

Phases of pertussis 

The illness has three phases.

First phase

During this phase, your child will begin to have cold-like symptoms, such as mild fever, a runny nose and cough. These symptoms last for about two weeks and are similar to those of many viral upper respiratory tract infections.

Second phase

In this phase, the cough gets worse. Your child will have severe coughing episodes. These are sudden short, fast coughs that occur in clusters. 

Coughing makes breathing difficult for your child. When your child takes a breath in after a cluster of coughs, you will hear a high pitched whooping sound. Children less than six months old typically do not whoop and may instead gasp or gag during coughing episodes. The coughing may also cause your child to vomit milk, food or mucus.

Your child will also often turn red in the face from coughing but will look relatively well between coughing episodes. 

This phase lasts from weeks two to six of the illness.

Third phase

This phase includes healing and recovery. Your child will continue to have a persistent cough, but it will be less severe than in the second phase. This phase can last from weeks to months.

Causes of pertussis

This illness is caused by the bacteria (germ) Bordetella pertussis. You can almost always prevent pertussis by having your child vaccinated. 

If you or your child has been vaccinated, the immunity (protection) offered by the vaccine can decrease over time. This is why it is important to get a booster vaccine. Adolescents and adults who do not get a booster vaccine can become infected and pass the infection to children. Babies who have not received their complete vaccination for pertussis are also at risk for getting the infection. They can get sick very quickly when exposed to others who have it.

Complications of pertussis

Pertussis can be harmful, especially for babies. Complications may include pneumonia, apnea (breaks in  breathing), seizures and death.

How pertussis is treated 

Your child will need to take antibiotics to fight the bacteria that cause pertussis. If your doctor thinks it is very likely that your child has pertussis, they will suggest that your child start the antibiotic even before their test results are confirmed. The antibiotics are most effective if started within three days of the start of illness. 

Make sure your child completes the full course of antibiotics, even if their symptoms seem to improve. People in close contact with your child may be asked to take an antibiotic so the infection does not spread. 

Caring for your child at home

Use a humidifier 

Humid air may help loosen mucus, while dry air tends to make coughs worse. A cool mist vaporizer or humidifier in your child's bedroom may help. Change the water and clean any filters at least once a day. 

Remove mucus with saline solution

Use a nasal saline solution and nasal suction to help remove mucus in the nose and throat. 

Adjust your child’s sleeping position

Keep your child upright before and after feeding to reduce spitting up and vomiting. This position also makes breathing easier. 

Offer small glasses of fluid often

Encourage your child to drink small amounts of fluids often. It is important to maintain hydration if your child is vomiting. Breastfed babies should continue breastfeeding.

Avoid smoky places

Keep your child away from smoke and other environmental irritants. Cigarette smoke can make coughs worse.

When to see a doctor

Call your child’s regular doctor if:

  • your child’s cough is persistent, getting worse or occurring in clusters 
  • your child has had contact with someone who has pertussis.

Go to your nearest Emergency Department or call 911 if:

  • coughing causes your child’s face to turn blue or your child to stop breathing
  • coughing makes breathing difficult or fast 
  • your child is not responding to you or seems lethargic (sluggish)
  • your child has a seizure (persistent shaking of the body that cannot be stopped)
  • your child is vomiting or not drinking and is getting dehydrated​.

Key points

  • Whooping cough can be a serious bacterial infection in children.
  • You can prevent pertussis by having your child vaccinated and getting a booster shot if needed. Ask your health care provider for advice.
  • Whooping cough can be treated with antibiotics. People who come in close contact with your child will need to take medication.
  • See your doctor if your child’s cough gets worse or occurs in clusters. Call 911 if your child’s cough makes breathing difficult or causes your child’s face to turn blue or if your child has a seizure. 

Shawna Silver, MD, FRCPC, FAAP, PEng