Side effects - How much K a day reccomended

[Synesthesiac]

swim and friend have a week with nothing much going on and a shiteload of special K, and for the last two days have been using K all day, about 0.5-1g each per day. Swim thinks there have been hardly any side effects so far, but was wonding if doing that much continually for a week or so would be advisable or if there would be side effects that start creeping in. Theres nothing toxic that builds up with recurrant use or anything is there?

Thanks.