Hello, after smoking a marijuana substitute, I have encountered blistering on the hands and arms. They are itchy and filled with clear liquid. Ideas?

Blisters. They could be sign if allergic reaction. Need examination to confirm the diagnosis. Please consult your GP or re post the question with a picture. .
Allergic skin reacti. called contact dermatitis. I suggest using 1% hydrocortisone cream on the affected skin and consulting your physician. Certainly, avoid this substance in the future.