Ceftriaxone is a broad-spectrum antibiotic that is frequently administered intramuscularly (IM) in emergency medicine. However, IM injections hurt — A LOT! Can we do anything to minimize the pain?

Trick of the Trade

Ceftriaxone for IM use can be diluted with lidocaine 1% [1]:

Ceftriaxone 250 mg vial – mix with 0.9 mL of lidocaine 1% = 250 mg/mL

Ceftriaxone 1000 mg vial – mix with 2.1 mL of lidocaine 1% = 350 mg/mL

What do the patients say?

In a double-blind crossover study [2], patients receiving IM ceftriaxone diluted with lidocaine 1% experienced 50% less pain compared to using sterile water for injection as a diluent. Using a 100 mm visual analog scale shortly after the shot, patients rated lidocaine-ceftriaxone pain as 25 mm compared to 50 mm for water-ceftriaxone. There was significant pain relief sustained up to 1 hour later.

How to Order

Depending on your institution, you may need to write two orders, i.e.,:

Ceftriaxone 250 mg IM x 1 Lidocaine 1% 0.9 mL, please use for ceftriaxone reconstitution (If a route for lidocaine is required, use “other” or “IM”)

Or just write,

Ceftriaxone 250 mg IM x 1, mixed with lidocaine 1%

Please check with your local pharmacist to see what is preferred in your emergency department.

And a reminder, if you have a functioning IV line, 250 mg of ceftriaxone for sexually transmitted infections can be administered IV instead of IM as previously posted on ALiEM.

References

Lexi-Comp Online (TM), Pediatric & Neonatal Lexi-Drugs Online (TM), Hudson, Ohio: Lexi-Comp, Inc.; January 29, 2011 Antimicrob Agents Chemother. 40(2): 485–487. PMID: 8834905

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