This allergic reaction is most likely a drug-related hypersensitivity reaction and not due to the anti-rabies vaccine or ERIG. Anti-rabies vaccines and ERIG are inactivated and purified preparations and are not affected by allergic reactions elsewhere in the body. Also, taking antihistamines like XL-Mont does not reduce or interfere with the effectiveness of the anti-rabies vaccine in any way. Your rabies protection remains fully intact.
The timing and pattern of symptoms suggest that the reaction was more likely triggered by one of the medications, especially Clavam (amoxicillin-clavulanate) or the Ondem/Drotin Plus injections, which are known to occasionally cause delayed allergic reactions, even if they were tolerated in the past. Allergic reactions can develop suddenly at any point in life, even to medicines previously taken safely. The generalized itchy rashes appearing within 30–60 minutes of injection strongly point toward a drug-induced urticarial reaction.
The good response to antihistamine confirms this was an allergic reaction. Mild residual redness may persist for 24–72 hours and usually settles on its own. There is no need to repeat or restart rabies vaccination, and no dose has been neutralized or lost. Continue the remaining rabies vaccine doses as per schedule.
Next Steps
For now, avoid Clavam and inform future doctors about this reaction. If itching persists, a non-sedating antihistamine once daily for a few days is sufficient.
Health Tips
Seek urgent care if there is facial swelling, breathing difficulty, or throat tightness, which are rare but serious signs.