What anti-nausea medication is recommended for someone experiencing heart palpitations (tachycardia)?

Anti-Nausea Medications for Patients with Heart Palpitations

For patients experiencing heart palpitations (tachycardia), metoclopramide is the preferred anti-nausea medication due to its minimal cardiac effects compared to other antiemetics. Ondansetron and other 5-HT3 antagonists should be avoided due to their potential to prolong QT interval and exacerbate arrhythmias.

First-Line Options

Metoclopramide

• Mechanism: Dopamine antagonist
• Dosing: 10mg IV/PO every 6-8 hours
• Advantages:
  • No significant effect on cardiac conduction
  • Does not prolong QT interval
  • Effective for most causes of nausea
• Caution: Monitor for extrapyramidal symptoms

Medications to Avoid

5-HT3 Antagonists (Ondansetron)

• AVOID in patients with heart palpitations/tachycardia
• Associated with QT prolongation and risk of torsades de pointes 1
• Can induce fatal ventricular tachycardia in susceptible individuals 2
• FDA warning regarding cardiac safety concerns 3

Phenothiazines (Promethazine, Prochlorperazine)

• AVOID or use with extreme caution
• Can prolong QT interval
• May cause hypotension and tachycardia

Alternative Options (When First-Line Not Suitable)

Diphenhydramine

• Can be used for mild nausea
• Less cardiac effects than 5-HT3 antagonists
• May cause sedation

Benzodiazepines

• For anticipatory nausea or anxiety-induced nausea
• Generally neutral cardiac profile
• Use lowest effective dose

Decision Algorithm

1. Assess cardiac status:

   • If patient has known arrhythmias, heart disease, or taking QT-prolonging medications → Avoid ondansetron completely

2. Evaluate nausea severity:

   • Mild to moderate: Metoclopramide 10mg
   • Severe: Consider combination therapy with metoclopramide + diphenhydramine

3. Monitor response:

   • If inadequate response and no worsening of palpitations → Increase metoclopramide dose (max 40mg/day)
   • If inadequate response with worsening palpitations → Switch to diphenhydramine

Important Considerations

• Obtain baseline ECG before administering any antiemetic in patients with palpitations
• Monitor heart rate and rhythm during treatment
• Many antiemetics can prolong QT interval, including ondansetron, which showed QT prolongation of 19.3 ± 18 msec in patients with cardiovascular disease 1
• The 2018 AHA/ACC/HRS guidelines for management of ventricular arrhythmias note that many medications can exacerbate arrhythmias 4
• Patients with heart failure or acute coronary syndromes are at particularly high risk for QT prolongation with ondansetron 1

Special Situations

• Chemotherapy-induced nausea: If metoclopramide insufficient, consider cardiology consultation before using ondansetron
• Post-operative nausea: Metoclopramide preferred; avoid ondansetron if palpitations present
• Pregnancy: Metoclopramide generally considered safe; avoid ondansetron if cardiac concerns exist

Remember that treating the underlying cause of palpitations is equally important as managing nausea symptoms.