[0] http://www.bbc.co.uk/newsbeat/article/29811499/k-bladder-the...
You would have to be taking grams and grams of the stuff on the regular; infrequent or one-off dosages won't cause bladder damage.
Edit: even in the article you can see that the guy developed "K bladder" after taking 15g per day. 15g is a truly scary amount of powder to be ingesting.
However, for use as an antidepressant, 100-200mg (0.1-0.2g) twice a month is sufficient, so it shouldn’t be an issue.
I will second that. A friend would use around that much and it would last almost 2 full weeks without feeling the need to take another 100mg. Once the 2 weeks hit though, he could feel his depression / anxiety coming back slowly.
Most of the studies of using ketamine to treat depression are using under 1 gram per month.
Infrequent use of ketamine (less than once a week, less than 1 g), whether medical or recreational has no negative side effects.
It's also unknown whether it's actually caused by ketamine, or by whatever is being used to cut street ket.
Ketamine is sourced pretty much exclusively from pharmaceutical manufacturers and is medical grade.
The recreational doses are also relatively small (10-50%) compared to anesthetic doses, too. Being unconscious isn’t the recreational user’s aim.
It's a problem, but seems to be limited to those exhibiting problem usage (even within the context of recreational use)