Final answer:
The sedating effect of antihistamines is not always an undesired side effect.
Step-by-step explanation:
The sedating effect of antihistamines is not always an undesired side effect. While it is true that antihistamines are often used to treat allergies and their symptoms, such as itching, sneezing, and nasal congestion, some antihistamines can cause drowsiness as a side effect. This sedating effect can actually be desired in certain situations, such as when someone is looking for relief from insomnia or motion sickness. Therefore, the statement is false.