Lidocaine Reconstitution for Intramuscular Ceftriaxone
Reconstitute 1 gram of intramuscular ceftriaxone with 3.6 mL of 1% lidocaine (without epinephrine) to reduce injection pain. 1
Standard Reconstitution Protocol
The CDC specifically recommends using 1% lidocaine solution (plain, without epinephrine) as the diluent when preparing ceftriaxone for intramuscular administration. 1 This practice significantly reduces the substantial pain associated with IM ceftriaxone injections.
Volume and Concentration Specifications
- Use 3.6 mL of 1% lidocaine to reconstitute 1 gram of ceftriaxone powder 1
- This creates a final concentration suitable for deep intramuscular injection into the gluteal muscle 1
- Never use lidocaine with epinephrine - only plain 1% lidocaine is appropriate 1
Evidence Supporting Pain Reduction
The use of lidocaine as a diluent provides clinically meaningful pain reduction compared to sterile water:
- Immediate post-injection pain is reduced by 3.84 points on a 10-point scale when lidocaine is mixed with the antibiotic versus sterile water 2
- Pain reduction persists at 5 minutes (2.85 points lower) and 20 minutes (1.85 points lower) after injection 3
- Significant pain differences are maintained up to 6 hours post-injection 2
A head-to-head comparison of IM ertapenem versus IM ceftriaxone (both reconstituted in lidocaine) showed comparable tolerability profiles, with only 1.1% of patients experiencing moderate-to-severe injection site symptoms with the lidocaine-reconstituted preparation. 4
Critical Safety Warnings
Never administer lidocaine-reconstituted ceftriaxone intravenously. 1 This reconstitution method is exclusively for intramuscular administration. If IV ceftriaxone is required, use sterile water or normal saline as the diluent. 1
Common Pitfalls to Avoid
- Do not use lidocaine with epinephrine, as vasoconstriction may impair antibiotic absorption 1
- Do not attempt to use topical lidocaine gel on the skin before injection - this provides no significant pain reduction (mean difference only -0.54 points, not statistically significant) 3
- Ensure proper deep gluteal injection technique to minimize tissue trauma 4
Clinical Context
This recommendation applies to the standard 1 gram IM dose of ceftriaxone used for conditions such as uncomplicated gonorrhea, disseminated gonococcal infection, or other infections requiring intramuscular administration. 5 The lidocaine reconstitution does not affect the antimicrobial efficacy of ceftriaxone. 2