Health Topic

Croup

Croup symptoms include difficulty breathing, a barking cough, and a hoarse voice. Children are at the highest risk. Learn more about croup.

Reviewed Reviewed by a registered pharmacistGeneral information

Also called: Spasmodic croup · Viral croup

Important: This page is general information, not medical advice. It does not recommend or prescribe any treatment. Always consult your doctor or pharmacist before starting, stopping or changing any medicine.

About Croup

Croup is an inflammation of the vocal cords (larynx) and windpipe (trachea). It causes difficulty breathing, a barking cough, and a hoarse voice. The cause is usually a virus, often parainfluenza virus. Other causes include allergies and reflux.

Croup often starts out like a cold. But then the vocal cords and windpipe become swollen, causing the hoarseness and the cough. There may also be a fever and high-pitched noisy sounds when breathing. The symptoms are usually worse at night, and last for about three to five days. Children between the ages of 6 months and 3 years have the highest risk of getting croup. They may also have more severe symptoms. Croup is more common in the fall and winter.

Most cases of viral croup are mild and can be treated at home. Rarely, croup can become serious and interfere with your child's breathing. If you are worried about your child's breathing, call your health care provider right away.

It sits within Children and Teenagers and Lungs and Breathing.

The lead U.S. institute for this subject is the Eunice Kennedy Shriver National Institute of Child Health and Human Development.

When to speak to someone. Reading about a topic cannot tell you whether it applies to you. Speak to a doctor or pharmacist if symptoms are severe, sudden, getting worse, or simply not going away — and seek emergency care immediately for chest pain, breathing difficulty, sudden weakness or confusion, or a serious allergic reaction.

Research on Croup

41 studies areregistered for this condition on ClinicalTrials.gov, the U.S. National Library of Medicine's public registry. A selection is below — the links go straight to the registry entry, not to a summary of ours.

What a registered study does and does not mean. Registration means a study exists and has been declared publicly. It says nothing about whether the treatment being tested works, is safe, or is available to you. Many studies find no benefit — that is what research is for. Never seek out an experimental treatment on the strength of a registry entry alone.

Research currently under way

Research already completed

Study data from ClinicalTrials.gov, a service of the U.S. National Library of Medicine. Retrieved 2026-07-30. Registry entries are supplied by study sponsors and investigators; ClinicalTrials.gov does not verify their scientific validity. PocketsInfo is not affiliated with, and not endorsed by, the NLM or the NIH.

Where to read more

Rather than paraphrase, we point you to the primary sources. Every link below is to a government health agency, a national institute or a recognised medical body — grouped by what you are trying to find out.

Learn More

Clinical Trials

Medical subject headings

Clinicians and researchers index this subject under Croup. These are the terms to use when searching medical literature.

This page is built from the MedlinePlus health topic record for Croup, a service of the U.S. National Library of Medicine (NLM), National Institutes of Health. Information is from MedlinePlus.gov. PocketsInfo is not affiliated with, and is not endorsed by, the NLM or the NIH. Retrieved 30 July 2026.