Chronic Cough with Uncertain Cause (Child)

Coughs are one of the most common symptoms of childhood illness. They most often occur as part of the common cold, flu, or bronchitis. This kind of cough usually gets better in 2 to 3 weeks. A cough that continues longer than 3 to 4 weeks may be from other causes.

If the cough does not improve over the next 2 weeks, your child may need more testing. Follow up with the healthcare provider as directed. Based on the exam today, the exact cause of your child’s cough is not certain. Below are some common causes for persistent cough.

Child's head and torso showing upper and lower respiratory tracts and upper digestive system.

Postnasal drip

A cough that is worse at night may be from postnasal drip. Extra mucus in the nose drains from the back of the nose to the throat and triggers the cough reflex. If postnasal drip has been present more than 3 weeks, it may be from a sinus infection or allergy. Common allergens include dust, smoke, pollen, mold, pets, cleaning products, room deodorizers, and chemical fumes. Over-the-counter antihistamines or decongestants may be helpful for allergies. Don't use these in children younger than 6 years of age unless they have been advised by your child’s healthcare provider. A sinus infection may need treatment with antibiotic medicine. See your healthcare provider if symptoms continue.


A cough may be the only sign of mild asthma. Your child’s healthcare provider may do tests to find out if asthma is causing the cough. Your child may also take asthma medicine on a trial basis.

Foreign object

Babies and young children who put small objects in their mouth can inhale them into the lungs. This may cause a severe coughing spell at first that becomes a chronic cough. Your child may also have slight wheezing or shortness of breath. This is a serious problem. If this is suspected, it must be checked by the healthcare provider.

Heartburn (acid reflux, GERD)

The esophagus is the tube that carries food from the mouth to the stomach. A valve at its lower end prevents the backward flow of stomach contents (reflux). When the valve does not work correctly, food and stomach acid flow back into the esophagus. This is also called GERD (gastroesophageal reflux disease).

When this flows as far as the mouth, it looks like spit up. This is not vomiting. It happens without any sign of retching. Signs of reflux in babies usually occur soon after eating. These signs include spitting up, vomiting, poor weight gain, fast or difficult breathing, and unusual fussiness or irritability. In older children, signs of reflux may include belching, vomiting, heartburn, stomach pain, acid or bitter taste in the mouth, and painful swallowing. See the healthcare provider for more testing if your child has these symptoms.


Strong coughing spells can cause gagging and vomiting during or right after the cough. When a cold is the cause of the cough, your child may swallow lots of mucus. This can cause nausea and vomiting. If repeated vomiting occurs, contact the healthcare provider.

Habit cough

Some children may cough or clear their throats as part of a problem with their nervous system or because of a mental health problem. This is also called habit cough or tic cough. This type of cough doesn’t have a clear physical cause. It usually stops when a child is asleep. Your child may need more assessment to find out if this is why your child is coughing. This assessment is usually done by a psychiatrist or a neurologist after other causes of a chronic cough have been ruled out.

Secondhand smoke

Young children who are exposed to tobacco smoke in their homes can have a chronic cough, as well as any of these symptoms:

  • Stuffy nose, sore throat, or hoarseness

  • Eye irritation, headache, or dizziness

  • Fussiness, loss of appetite, or lack of energy

Babies and children younger than 2 years who are exposed to cigarette smoke have a higher risk for these conditions:

  • Ear and sinus infections and hearing problems

  • Colds, bronchitis, and pneumonia

  • Croup, influenza, bronchiolitis, and asthma

In children who already have asthma, secondhand smoke increases the number and severity of asthma attacks. Secondhand smoke is a serious health risk for your child. You must do what you can to prevent the exposure.

Follow-up care

Follow up with your child’s healthcare provider, or as advised, if your child’s cough does not get better. Your child may need more testing.

Note: If an X-ray was taken, a specialist will review it. You will be told of any new findings that may affect your child’s care.

When to seek medical advice

For a usually healthy child, call your child's healthcare provider right away if any of these occur:

  • Fever (see Fever and children, below)

  • Whooping sound when breathing in after a long coughing spell

  • Coughing up dark-colored sputum (mucus)

  • Noisy breathing

Call 911

Call 911 if any of these occur:

  • Coughing up blood

  • Wheezing or difficulty breathing

  • Blue, purple or gray color or tint to the lips or fingernails

  • Unresponsive or dizziness

  • Fast breathing:

    • Birth to 6 weeks, over 60 breaths per minute

    • 6 weeks to 2 years, over 45 breaths/minute

    • 3 to 6 years, over 35 breaths/minute

    • 7 to 10 years, over 30 breaths/minute

    • Older than 10 years, over 25 breaths/minute

Fever and children

Use a digital thermometer to check your child’s temperature. Don’t use a mercury thermometer. There are different kinds and uses of digital thermometers. They include:

  • Rectal. For children younger than 3 years, a rectal temperature is the most accurate.

  • Forehead (temporal). This works for children age 3 months and older. If a child under 3 months old has signs of illness, this can be used for a first pass. The provider may want to confirm with a rectal temperature.

  • Ear (tympanic). Ear temperatures are accurate after 6 months of age, but not before.

  • Armpit (axillary). This is the least reliable but may be used for a first pass to check a child of any age with signs of illness. The provider may want to confirm with a rectal temperature.

  • Mouth (oral). Don’t use a thermometer in your child’s mouth until they are at least 4 years old.

Use the rectal thermometer with care. Follow the product maker’s directions for correct use. Insert it gently. Label it and make sure it’s not used in the mouth. It may pass on germs from the stool. If you don’t feel OK using a rectal thermometer, ask the healthcare provider what type to use instead. When you talk with any healthcare provider about your child’s fever, tell them which type you used.

Below are guidelines to know if your young child has a fever. Your child’s healthcare provider may give you different numbers for your child. Follow your provider’s specific instructions.

Fever readings for a baby under 3 months old:

  • First, ask your child’s healthcare provider how you should take the temperature.

  • Rectal or forehead: 100.4°F (38°C) or higher

  • Armpit: 99°F (37.2°C) or higher

Fever readings for a child age 3 months to 36 months (3 years):

  • Rectal, forehead, or ear: 102°F (38.9°C) or higher

  • Armpit: 101°F (38.3°C) or higher

Call the healthcare provider in these cases:

  • Repeated temperature of 104°F (40°C) or higher in a child of any age

  • Fever of 100.4° F (38° C) or higher in baby younger than 3 months

  • Fever that lasts more than 24 hours in a child under age 2

  • Fever that lasts for 3 days in a child age 2 or older

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