My son is 8 years old and has been prone to croup since he was very young. Croup is a swelling of the vocal cords and air ways much as asthma is the swelling of the bronchial tube and lungs. Because a child's airways are still so small any amount of swelling can cause them to not be able to breath at all or very poorly at best. It's caused by a virus, typically it's the type that gives adults laryngitis. Decongestants and pain relievers are not going to treat it, though a cough medicine helps with some of the symptoms but not all. While there are home remedies to help lessen the severity of the symptoms it really needs medical treatment like asthma does. I have been in for many emergency doctor visits because of my son's croup attacks. Before we kept a doctor prescribed steroid, brand name Orapred though there is a generic, in the refrigerator at all times to give him at the first croup attack it could go on for days and require emergency trips, nebulizer treatments and more misery and being totally scared witless hoping your baby doesn't stop breathing altogether. In all his life he's only had to take more than a single dose perhaps twice.
We are a family who does not take medicine lightly. I am highly allergic to a very long list of commonly used medicines, some of which have cause shock and almost death. We don't even take Tylenol lightly. But in the case of treating croup, at that first attack we go straight to the refrigerator and give him a dose of the steroid. There have been studies done that have proven that when taken with the first attack the length and severity of the croup lessens dramatically. Our doctor is very much the kind who also does not prescribe medicines on a whim.
To treat the symptoms, sitting in a bathroom with the doors and windows closed and run the hot water letting him breathe in the steam helps relax the swelling so he can breathe a bit better. Keeping a cool mist humidifier in his bedroom will also relieve some of it. My husband will often take them to go sit in the car at night with the windows down to help relax the airways. The problem with only treating the symptoms is you're not treating the cause and the swelling may very well come back. I can remember suffering for up to 4 nights in a row, my son sleeping in our bed so when he's have another attack, often only hours apart, I could sit him up and keep him breathing. This was before we got the steroid.
Here is a wonderful article from Dr Sears' website on croup http://www.askdrsears.com/html/8/T084200.asp
They do start to outgrow it. Though my 8 year old does still get attacks he gets far less and they are less severe then when he was really young. My other son who's 5 has only had it a small handful in his entire lifetime.
Best of luck!