Which symptom should alert a nurse to the possibility of digoxin toxicity?

Nausea and vomiting are common symptoms that can indicate digoxin toxicity. Digoxin, a medication often used to treat heart conditions, has a narrow therapeutic index, meaning the difference between an effective dose and a toxic dose is small. When digoxin levels in the body become too high, it can lead to gastrointestinal symptoms such as nausea, vomiting, and loss of appetite, making these symptoms significant warning signs for toxicity.

The presence of nausea and vomiting signals that the medication may be affecting the gastrointestinal system, which is often one of the first areas to be impacted by elevated levels of digoxin. Recognizing these symptoms early can allow for prompt evaluation of the patient's digoxin levels and potential adjustment of the medication regimen to prevent more serious complications.

Weight gain might suggest fluid retention or heart failure worsening but is not directly indicative of digoxin toxicity. An increased heart rate could indicate various cardiovascular conditions, including digoxin toxicity, but it is not the most specific symptom. Increased urine output could occur due to other factors, such as diuretics or improved heart function, and is not associated with toxicity. Therefore, nausea and vomiting stand out as the most relevant and specific indicators of digoxin toxicity among the options provided.