Brief Answer: Better to use a new one... Detailed Answer: Hi, Shelf life of drugs/compounds (expiry date) are determined after plenty of research studies. Though some drugs retain its full potential a few days to month after the shelf life, whether or not the drug in discussion (trimix injection) would be able to give its full benefit is unpredictable. Therefore I always discourage my patients from using expired product. If you wish for maximum benefits from this injection, it is better to use fresh injection and not one that is expired (even if it recently expired). Hope this helps. Let me know if you need clarifications. Regards

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