Decongestants can sometimes make children jittery because the drug is closely related to adrenaline. In particular, small children and infants are susceptible to this effect. Most physicians agree that children under the age of 6 months should avoid taking decongestants. Older children should try to take decongestants formulated for kids. To receive the proper dosage, parents should make sure their child’s physician is aware of the child’s age.

With children, physicians will often recommend a nasal spray decongestant rather than an oral decongestant. This is because nasal sprays treat a concentrated area, which reduces the amount of decongestant that is passed into the rest of the child’s body. This helps limit side effects.
It is very important that children understand that they should use nasal sprays only as directed. Using a spray longer or more frequently than directed can result in rebound congestion (rhinitis medicamentosa), which consists of nasal swelling and congestion. Some children may overuse their sprays unless carefully supervised.

Though there have been no studies to evaluate the use of decongestants among the elderly, older users are generally believed to be more likely to experience side effects when taking this type of drug. For this reason physicians often recommend that users of decongestants – particularly those using pseudoephedrine (a common ingredient in decongestants) – who are over 60 use a short-acting form of the drug to reduce the chance of side effects. Older users should refrain from using a controlled-release or long-acting form of the drug.