Which statement about decongestants is not true?

Decongestants are primarily used to relieve nasal congestion, and they function by constricting blood vessels in the nasal passages. This action decreases swelling and congestion, making statement one accurate. However, decongestants can indeed cause an increase in blood pressure, particularly in sensitive individuals, which justifies the truth of the second statement.

The concern regarding the safety of decongestants for individuals with diabetes mellitus arises because these medications can occasionally stimulate the adrenergic receptors, leading to increased blood glucose levels or affecting blood pressure. Therefore, they may not be the safest option for all individuals with diabetes, making the assertion that they are very safe for this population not true.

The potential for rebound congestion is also a well-documented issue with long-term use of decongestants, especially topical ones, making that statement accurate as well. Thus, the incorrect assertion about the safety of decongestants for people with diabetes helps clarify the nuances of their use and the need for caution in this demographic.