A client taking ethambutol (Myambutol) should report which of these symptoms to indicate understanding of the medication?

Understanding the side effects of ethambutol, it is important to note that one of its significant adverse effects is related to vision, specifically affecting color perception. Ethambutol can cause a condition known as optic neuritis, which may result in difficulty distinguishing between the colors red and green. This side effect should be reported by the client, as it indicates a potential complication related to the medication that may require further evaluation or adjustment of treatment.

In contrast, while impaired hearing, gastrointestinal discomfort, and discoloration of bodily secretions can be side effects of other medications or conditions, they are not the primary concerns associated with ethambutol specifically. Therefore, the correct answer reflects a key understanding of the medication's unique side effects, demonstrating the importance of monitoring vision and color perception in clients taking ethambutol.