Hyper, anxious, weight gain, high blood pressure: I started taking Singulair in January after having some kind of allergy reaction to either the cats or something else. My GP suggested that I take it every day -but I'm quitting today. I have been so hyper the last three weeks and feeling -not well. It's like I'm off filled with dread and anxiety. Last week I ended up in the hospital with heart attack symptoms and with incredible anxiety,hyperness and high blood pressure! I never had any of these symptoms before then. I am healty cook and eater, a non-smoker, and was within 25 pounds of my normal weight for a 56 year old. Yes, it's gotta be the Singulair. It's the only medication that's changed. J. Haggerty