What's in your nasal spray? Because these are sold over the counter, most people assume all the spray products and inhalers have been vetted by the FDA and are safe. Unfortunately, that's not always the case.

Some sprays, when used for more than a few days straight, can cause “nasal spray addiction.” Although not a true addiction, such sprays can cause damage to the sensitive tissue inside the nose, causing swelling and long-term stuffiness – just the condition the spray may have been intended to relieve.

Saline sprays are by far the safest, and not addictive, as they typically just contain salt and sterilized water. Some brands may contain preservatives that prevent the growth of mold or bacteria. Often, manufacturers offer preservative-free formulas in aerosol cans that keep the liquid sterile. Look for the terms “drug-free” or “saline” on your spray's label, and be sure the main ingredient is listed as sodium chloride. The spray should not have any “active” ingredients.

Which is not to say that all non-saline sprays are harmful or addicting. Other sprays contain corticosteroids designed to reduce inflammation caused by an overactive immune system response. Conditions such as hives, skin rashes from allergies or bites, asthma, and nasal allergies can be treated with various types of corticosteroids administered via a spray.

Corticosteroids sprayed into the nose are usually intended to treat nasal allergy symptoms such as sneezing and a runny nose. They are often viewed as a more direct approach than medications taken orally.

Corticosteroid sprays take a few days to kick in, and usually must be taken daily throughout allergy season. Side effects may include nosebleeds, eye conditions such as cataracts, and headaches.

Corticosteroid sprays are not addictive, but this does not mean they come without caveats. Some types of corticosteroids – those that contained a type of corticosteroid called fluticasone furoate – may slow growth in children, especially if used for a long time. Children should only use steroid nasal sprays under the guidance of a doctor for this reason.

Antihistamines – a third type of nasal spray – block a chemical called histamine that is responsible for allergy symptoms such as sneezing, itching, and runny noses. Antihistamines are also available in pill form, but many people prefer the nasal spray as it may cause fewer side effects. Antihistamine nasal sprays are not addictive, and may be used for up to 12 weeks without any prescription by a doctor. Antihistamines are not addictive.

The nasal spray problem children are the decongestants. The can cause a condition known as rebound congestion, described colloquially as spray addiction. Each time a decongestant is used, it narrows the blood vessels in the nose, causing the tissue inside the nose to shrink. After the medicine wears off, the nasal tissue swells again, sometimes swelling even more than before. With continued use, this swelling can get more severe and lead to permanent swelling of the tissue. Long-term use of these sprays can also damage the tissue, causing infection and pain.

The symptoms of nasal spray addiction may include:

Feeling congested again shortly after using a decongestant spray
Using a decongestant spray regularly but feeling that it doesn't work anymore
Feeling a strong urge to use the spray more often than directed
Using the spray just to be able to breathe normally on a daily basis

The American Academy of Asthma, Allergy and Immunology recommends using decongestants for no more than twice a day for only 3 days, in order to avoid nasal spray addiction.