*This statement summarizes the third USPSTF recommendations for screening for chlamydial infection and the supporting scientific evidence, and it updates the 1995 recommendations contained in the Guide to Clinical Preventive Services, second edition (1).
What are the possible side effects of levothyroxine (Levothroid, Levoxyl, Synthroid, Tirosint, Unithroid)? Get emergency medical help if you have any of these signs of an allergic reaction: hives; difficult breathing; swelling of your face, lips, tongue, or throat. Call your doctor at once if you have a serious side effect such as: headache;
Re: how long does it take for levothyroxine to start working after taking it. I started on 25 mg of synthroid about 1 year ago (TSH level was about 9) and definitely felt positive effects, like more focused and energized, after about 3-4 months i was put on 50mg and still felt ok.