Which of the following is an effect of acetaldehyde build-up caused by disulfiram?

The build-up of acetaldehyde caused by disulfiram primarily leads to flushing and nausea as its most notable effects. Disulfiram works by inhibiting the enzyme aldehyde dehydrogenase, which is crucial for metabolizing acetaldehyde—a byproduct of alcohol metabolism. When alcohol is consumed while taking disulfiram, acetaldehyde accumulates in the body, leading to unpleasant symptoms such as facial flushing, rapid heartbeat, nausea, vomiting, and palpitations. These adverse effects serve as a deterrent to drinking alcohol, reinforcing the treatment's aim to support patients in maintaining sobriety.

In contrast, the other options do not align with the physiological reactions associated with acetaldehyde accumulation. Increased appetite and euphoria are not typical responses to disulfiram treatment and do not result from acetaldehyde build-up. Instead, these symptoms would be more likely associated with compounds or situations that either promote or reward alcohol consumption rather than deter it. Weight loss might occur in some individuals due to reduced alcohol intake, but it is not a direct effect of acetaldehyde itself.