Why is hydroxyzine (an antihistamine) preferred over metoclopramide (a dopamine antagonist) for nausea during a migraine attack?

Hydroxyzine vs. Metoclopramide for Migraine-Associated Nausea

Hydroxyzine may be preferred over metoclopramide for nausea during migraine attacks due to its dual antiemetic and sedative properties, which can help with both nausea and anxiety/insomnia that often accompany migraines, while avoiding the extrapyramidal side effects associated with metoclopramide.

Metoclopramide for Migraine-Associated Nausea

• Metoclopramide, given intravenously, has fair evidence as monotherapy for acute migraine attacks, particularly in patients with nausea and vomiting 1
• Metoclopramide not only treats accompanying nausea but also provides synergistic analgesia for migraine pain 2
• However, metoclopramide carries risk of extrapyramidal symptoms including dystonia and akathisia 3
• In network meta-analyses, metoclopramide showed significant improvement in headache outcomes compared to placebo and sumatriptan, but was less effective than some other agents like granisetron 3

Antihistamines for Migraine-Associated Nausea

• Antiemetics should not be restricted to patients who are vomiting or likely to vomit; nausea itself is one of the most aversive and disabling symptoms of a migraine attack 1
• Treatment of nausea and vomiting with an appropriate antiemetic is specifically recommended in migraine management guidelines 1
• Antihistamines like hydroxyzine have sedating properties that can be beneficial during a migraine attack, helping patients rest while managing nausea 1

Advantages of Hydroxyzine Over Metoclopramide

1. Fewer extrapyramidal side effects:

   • Hydroxyzine does not cause the dystonia or akathisia that can occur with metoclopramide 3
   • Metoclopramide has been associated with higher incidence of mild side effects compared to some other medications 3

2. Dual therapeutic effect:

   • Hydroxyzine provides both antiemetic effects and anxiolytic/sedative properties 2
   • This dual effect can address both nausea and the anxiety or insomnia that often accompany migraine attacks 1

3. Treatment timing considerations:

   • When sedation side effects are not a concern, hydroxyzine's sedative properties may actually be beneficial for patients during a migraine attack 1
   • This can help patients rest during the attack, potentially improving overall comfort 2

Treatment Algorithm for Migraine-Associated Nausea

1. First-line approach:

   • For mild to moderate migraine with nausea: NSAIDs plus an antiemetic (hydroxyzine preferred over metoclopramide when sedation is not a concern) 1
   • For patients with significant nausea: Consider non-oral route of administration 1

2. When to choose hydroxyzine:

   • When patient can benefit from sedation (evening/nighttime attacks) 1
   • When patient has history of anxiety with migraines 2
   • When patient has had previous adverse reactions to metoclopramide 3

3. When to choose metoclopramide:

   • When sedation must be avoided (daytime attacks when alertness is required) 1
   • When prokinetic effects are specifically desired to improve absorption of oral migraine medications 4
   • When intravenous administration is being used in emergency setting 5

Important Considerations

• Medication-overuse headache can result from frequent use of acute medications (more than twice weekly) 1, 2
• Treatment choice should be individualized based on attack severity, associated symptoms, patient history, and medication response 1
• For patients with significant nausea and vomiting, non-oral routes of administration should be considered 1, 4
• Antiemetics should be used not just for vomiting but also for nausea itself, which is a disabling symptom of migraine 1

By considering these factors, clinicians can make an informed choice between hydroxyzine and metoclopramide for treating nausea during migraine attacks, with hydroxyzine often being preferred for its dual antiemetic and anxiolytic properties when sedation is acceptable or beneficial.