I definitely don't think it's normal but my doc said it wasn't too terrible uncommon/bad so I am not really nervous about it. It's just something I've noticed over the years. It's about 10 years since the last time I had penicillin (had antibiotic drip last month but that was while I was high out of my mind on morphine and anasthesia so I don't remember that too well!) but I remember that if I had some kind of inflamation and took penicilin, the trip would start exactly about 2 minutes after taking the pills and would last 30 minutes if I was lucky and more than an hour if I was unlucky. I usually would be sent back to school and then told to finish the prescription and whenever I had to take penicillin at the end of lunch, my next two classes would just be me trying my darndest to keep myself together without having a mental breakdown haha. I have no idea if I had some kind of allergic reactions? or if it was placebo effect to the fullest but something DID happen!