Symptoms and causes


Croup often begins as a typical cold. If there is enough inflammation and coughing, a child will develop a loud barking cough. This often is worse at night, and is further aggravated by crying and coughing, as well as anxiety and agitation, setting up a cycle of worsening symptoms. Fever and a hoarse voice are common, too. Your child's breathing may be noisy or labored.

Because children have small airways, they are most susceptible to having more marked symptoms with croup, particularly children younger than 3 years old.

Symptoms of croup usually last for three to five days.

When to see a doctor

Approximately 5 percent of children seen in the emergency department for croup require hospitalization. You should seek immediate medical attention if your child:

  • Makes noisy, high-pitched breathing sounds (stridor) both when inhaling and exhaling
  • Begins drooling or has difficulty swallowing
  • Seems anxious and agitated or fatigued and listless
  • Breathes at a faster rate than usual
  • Struggles to breathe
  • Develops blue or grayish skin around the nose, mouth or fingernails (cyanosis)


Croup is usually caused by a virus infection, most often a parainfluenza virus.

Your child may contract a virus by breathing infected respiratory droplets coughed or sneezed into the air. Virus particles in these droplets may also survive on toys and other surfaces. If your child touches a contaminated surface and then touches his or her eyes, nose or mouth, an infection may follow.

Risk factors

Most at risk of getting croup are children between 6 months and 3 years of age. The peak incidence of the condition is around 24 months of age.


Most cases of croup are mild. In a small percentage of cases, the airway swells enough to interfere with breathing.

Dec. 19, 2015
  1. AskMayoExpert. Croup. Rochester, Minn.: Mayo Foundation for Medical Education and Research; 2015.
  2. Woods CR. Croup: Approach to management. Accessed Oct. 9, 2015.
  3. Zoorob R, et al. Croup: An overview. American Family Physician. 2011;83:1067.
  4. Russell KF, et al. Glucocorticoids for croup. Cochrane Database of Systematic Reviews. Accessed Oct. 9, 2015.
  5. Petrocheilou A, et al. Viral croup: Diagnosis and a treatment algorithm. Pediatric Pulmonology. 2014;49:421.
  6. Kawaguchi A, et al. Evidence for clinicians: Nebulized epinephrine for croup in children. Paediatrics and Child Health. 2015;20:19.
  7. Thompson M, et al. Duration of symptoms of respiratory tract infections in children: Systematic review. BMJ. 2013;347:f7027.
  8. OTC cough and cold products: Not for infants and children under 2 years of age. U.S. Food and Drug Administration. Accessed Oct. 9, 2015.
  9. Barbara Woodward Lips Patient Education Center. Croup. Rochester, Minn.: Mayo Foundation for Medical Education and Research;2012.
  10. Woods CR. Croup: Clinical features, evaluation, and diagnosis. Accessed Oct. 14, 2015.
  11. Human parainfluenza viruses (HPIVs). Centers for Disease Control and Prevention. Accessed Oct. 22, 2015.
  12. Woods CR. Croup: Pharmacologic and supportive interventions. Accessed Oct. 22, 2015.