Warning! Never take medication prescribed for someone else, and ...

Warning! Never take medication prescribed for someone else, and always check for serious side effects. Since having chest and sinus congestion for three months, I decided to take my son's left over guaifenex. After three days, I experienced heart palpitations unlike anything else before. I also had a weird cold sensation, extremely hard to warm up. After a night's sleep, my heart rate has not yet returned to normal. I am horrified to know that this potentially harmful medication was prescribed to my then 11 yr. old child.