Permanent brain damage after IV 3-mmc?

A buddy and I did about six injections over the course of the night. I'm currently on harm reduction, including sleep, liquids, healthy foods, I also took some weed and a benzo to ease the comedown.

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What I was wondering, is if injecting 3-mmc causes irreversible brain damage, especially compared to other routes of administration?

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Also, unfortunately I broke a rule of myself to at least keep a minimim of 3 months inbetween using. I use it recreationally 3 times max a year. My last use was however only a month ago. Does thIs increase the risk of brain damage?