Written by Aaron Lacy
When compared to placebo, a combination of metoclopramide and diphenhydramine was effective at reducing posttraumatic headache.
Why does this matter?
Traumatic injury is a bread and butter ED presentation, and posttraumatic headache often accompanies this chief complaint. We use metoclopramide + diphenhydramine to treat migraine headaches; could it work for posttraumatic?
TLC is better with M + D
In this randomized, double blinded, placebo-controlled trial, patients with moderate to severe posttraumatic headache (<10 days since head injury) were randomized to IV metoclopramide 20mg plus IV diphenhydramine 25mg (M+D) or placebo. 81 patients in the M+D group reported a 5.2 reduction in pain score (SD 2.3) on the 0-10 analog pain scale compared to a 3.8 (SD 2.6) reduction in the 79 patients in the placebo group 1 hour after administration. There was no difference in pain at 1-week post administration. Notably there were more reported side effects in the M+D group (43%) than placebo (28%).
M+D helps reduce pain from migraines, so it makes sense that it would work for other headache types as well. However, there was a 43% rate of adverse events (drowsiness, akathisia, diarrhea), which seems high to me. Given this rate of adverse events, I would be interested to see a RCT comparing M+D to I+A (ibuprofen + acetaminophen). Regardless, this is an interesting idea to keep in your tool belt for treating the posttraumatic headache patient who says they have already tried over the counter medications.
Randomized Study of Metoclopramide Plus Diphenhydramine for Acute Posttraumatic Headache. Neurology. 2021 Mar 24;10.1212/WNL.0000000000011822. doi: 10.1212/WNL.0000000000011822. Online ahead of print.