In one sentence, describe what the following article is about:

Most cases of croup are able to be treated at home, but if your child is still sick after 48 hours, has a stridor, or if their symptoms worsen, call your doctor. Most cases of croup are caused by a virus, so antibiotics will not be effective. However, your doctor may be able to prescribe medicines to ease your child's breathing and treat their symptoms.  Ask whether a steroid (glucocorticoid) would be beneficial for your child. These steroids help to reduce inflammation in the airways and make it easier to breathe. Inquire if a nebulizer treatment (breathing treatment) would be beneficial. A nebulizer vaporizes the medicine which the child then breathes in through a mask. This is a common treatment for children with croup. These tests would help to confirm the diagnosis of croup and to make sure your child doesn't have another illness with similar symptoms. These are rarely necessary, but if your child's condition is worsening, discuss these tests with your doctor. Usually, using steroids or other medications to ease breathing and treat the cough is sufficient to help your child begin to feel better. Croup will usually resolve on its own, so treating the symptoms is enough. However, blood tests and x-rays are an option if your child does not seem to be getting better. If your child is dehydrated or has very labored breathing, they need immediate medical help. Signs of dehydration include reduced urination, few or no tears when crying, a dry or sticky mouth, or sunken eyes. If your child has these signs, or if they are having extreme difficulty breathing, take them to the emergency room or call for paramedics. Seek immediate medical attention if your child has bluish tinges to lips or fingernails, cannot swallow due to a swollen throat, or if they show signs of retraction (their neck or chest muscles pull in when they breathe).

Summary:
Visit a doctor if the symptoms lasts longer than 48 hours. Ask your doctor if blood tests or x-rays are necessary. Know when to seek immediate medical attention.