Which of the following is a non-specific sign of digoxin toxicity?

Visual disturbances are indeed a non-specific sign of digoxin toxicity. This can manifest as changes in vision, such as blurred vision, yellow or green halos around lights, or other alterations in visual perception. Recognizing these disturbances is critical because they can indicate elevated digoxin levels in the body, which may lead to significant and potentially life-threatening effects if not addressed promptly.

Though the other options may also suggest various medical issues, they are less directly tied to digoxin toxicity. Joint pain, for instance, could suggest musculoskeletal problems or inflammatory conditions but is not commonly associated with digoxin's effects. A rash may indicate an allergic reaction or dermatological condition unrelated to digoxin. Increased sweating might be a general symptom of various conditions but does not specifically point to digoxin toxicity. Therefore, visual disturbances are more closely and definitively linked to the effects of digoxin.