Are symptoms like fainting and feeling hot normal with lysine supplement?

Fainting and feeling hot are not listed among the side effects of L-lysine supplements. When taken in high doses, however, L-lysine supplements may cause gastrointestinal problems including nausea, stomach cramps and diarrhea and may increase your risk for gallstones and kidney problems. If you have liver or kidney problems, don’t take L-lysine without talking to your doctor. 

L-lysine supplements are sometimes recommended for people who don't consume enough of the amino acid lysine in their diets. Lysine is found in a number of foods, including meat, fish, eggs, beans, and nuts. Consult your doctor before taking L-lysine or any other dietary supplement.

This is not a typical reaction to taking lysine supplements and needs to be reported and evaluated by the doctor to determine its cause. There could be other causes for the fainting and your doctor needs to make a full health assessment. You should not take Lysine in any form until you have seen the doctor. You may also want to contact the store you purchased the lysine supplements from and assure they were indeed lysine and not labeled in error. There may also be a manufacturer's hotline listed on the bottle and you should report this adverse reaction to the company.