Which of the following antihistamines is noted for potentially causing tachyphylaxis?

The correct response highlights cetirizine as an antihistamine that may lead to tachyphylaxis, which is a rapid decrease in response to a drug after its initial administration. Cetirizine, a second-generation antihistamine, is known for its efficacy in treating allergic conditions but can cause a diminished response over time due to the receptor desensitization that occurs with ongoing use.

In contrast, other antihistamines listed do not show a significant propensity for tachyphylaxis. Loratadine, fexofenadine, and levocetirizine are generally well-tolerated and maintain their effectiveness with continued use. They minimize the potential for forming tolerance, which distinguishes them from cetirizine. Understanding this characteristic of cetirizine can guide practitioners in managing long-term treatment for allergic rhinitis and other allergic conditions effectively.