Is it safe to give my three-year-old toddler a nasal decongestant spray when she has a cold to help her breathe easier? I usually stay away from most mechanical medicines, since I find that it makes her hyper and interferes with her sleep. I do rub a little Vicks on her chest and she sleeps with an extra small pillow to keep her head elevated.
Although parents often ask about using them, I do not routinely recommend decongestant nose sprays, especially for this age group. As you correctly point out, side effects are less when medicines are given locally and don't get into the body's system. However, even if your toddler will tolerate squirting medicine up her nose, the decongestant nose sprays may be helpful for only a couple of days or so at best. The medication initially causes vasoconstriction (a narrowing of blood vessels in the nose) which helps shrink the tissues around it, opening the nasal passages. One then encounters a "rebound" effect where these blood vessels tend to swell; the whole area gets blocked up, and patients seem more congested than less.
The variety of cold preparations available in pharmacies really do not treat the common cold well and don't make it go away faster anyway. Most parents are just trying to relieve the symptoms, so their children are more comfortable and can get their rest. Some suggest merely using a vaporizer or humidifier in the room at naps and bedtime, which tends to increase the amount of moisture (humidity) in the air of the room. This may help to open the nasal passages and make your daughter's breathing easier. If you choose an oral (by mouth) over-the-counter decongestant instead, try cutting the usual recommended dose for your daughter in half. This should minimize the hyperactivity and be less disruptive to her sleep, but hopefully still give the desired relief.