GBL - Headaches and irritability anyone?

[Alkaran]

SWIM has taken GBL on and off for about 3 months now and recently has started taking 2x 5ml doses per night mixed with pure fruit juice. Aside from SWIMs tolerance seeming to increase (1 month ago he used to pass out after 3.5 ml) SWIM has noticed that he is generally more irritable and moody. Plus SWIM sometimes gets headaches - like some kind of mild hangover. Additionally SWIM and a friend have noticed that GBL seems really harsh on the kidneys. This is evident from the bad backs they both seem to get if they drink anything other than water.

We know SWIMs electrolyte levels are pretty okay. He eats bananas for his potassium (plus the amounts that he gets from the raising agents used in cereals, e.g. potassium hyrogen carbonate). Sodium may be a little low on as SWIM's diet is low in salt and he does suffer from low blood pressure.

Point is - does anyone else notice these side effects?