What adverse reaction may occur with the use of expectorants?

Nausea is a recognized adverse reaction that can occur with the use of expectorants. These medications are designed to help clear mucus from the airways, and while they can be effective in alleviating symptoms of congestion, they can also irritate the gastrointestinal tract in some individuals. This irritation can lead to feelings of nausea or an upset stomach, which is why nausea is a common side effect associated with expectorants.

The other options, while potentially linked to other classes of medications or conditions, are not typical adverse reactions of expectorants. For example, insomnia and anxiety are generally associated with stimulants or certain medications affecting the central nervous system, whereas visual disturbances often relate to medications with anticholinergic properties or those affecting vision directly. Thus, nausea stands out as the primary adverse reaction noted for expectorants.