I've been on 25mcg and 50mcg of levothyroxine on alternate days for years (maybe 15 - 20?); my doctor stopped it in February. She has now agreed I need it, so I've restarted and wonder how long it takes to notice an improvement? Officially I am within range on T4, but at the low end. My main symptom has always been depression, and the last few weeks I've been weeping at everyone several times a day.