Ditto, and I’d add that sensitivity to antihistamine side effects varies dramatically from person to person. I spent a long time thinking I had a sleep disorder, and was prescribed modafinil for years, but it turned out to be mainly a combination of zyrtec + depression (plus a few other contributors, but these were the largest non-genetic factors). I’d been on either zyrtec or claritin every day since I was ~8 years old, and they only started causing these kinds of problems in my early 20s. Now even Allegra D or olopatadine cause drowsiness and emotionlessness for me if I take them for more than a day or two at a time. (Flonase helps me but causes bloody noses, montelukast seems to have no side effects but provides minimal benefit for me. Planning on getting surgery later this year to try and improve my breathing.)
Ditto, and I’d add that sensitivity to antihistamine side effects varies dramatically from person to person. I spent a long time thinking I had a sleep disorder, and was prescribed modafinil for years, but it turned out to be mainly a combination of zyrtec + depression (plus a few other contributors, but these were the largest non-genetic factors). I’d been on either zyrtec or claritin every day since I was ~8 years old, and they only started causing these kinds of problems in my early 20s. Now even Allegra D or olopatadine cause drowsiness and emotionlessness for me if I take them for more than a day or two at a time. (Flonase helps me but causes bloody noses, montelukast seems to have no side effects but provides minimal benefit for me. Planning on getting surgery later this year to try and improve my breathing.)