I am so glad I found this posting! Hi everyone my names Vanessa..I am 20 years old and was prescribed doxycycline for mild adult acne in Jan..5 months ago...and never knew how much the side effects change someones lives. Experienced: insomnia, nightmares, hot/cold spells, difficulty breathing, paranoid, swollen face and tongue, crying spells, severe mood swings, inability to concentrate, weakness, fatigue, suicidal, shakiness, nausea, vomiting, diarrhea, irritability, feeling outside of my body.....it wasn't until I started to stop drinking coffee and drinking loads of water and exercising..that I realized it was the doxycycline side effects. I would wake up have a good breakfast....and water....than take the pill and start to get blurred vision...shaky..feel depressed. and confused...than I would start drinking more water and trying to sweat (knowing that water flushes toxins out of your body and sweating) and by 2 ish? the side effects subsided...and I could see clear. Today my first day not taken the pill...and from what I read it takes a few weeks to get it completely out of your system. But I get a kick out of doctors who prescribe all of these medications to people thinking it cures things..not realizing that it really can disrupts someones lives who's sensitive to medication.