Dangerous side effects or death can occur from the misuse of this medicine, especially if you are taking any other weight-loss medications or appetite suppressants. Before taking this medicine Synthroid should not be used to treat obesity or weight problems. Our Synthroid Side Effects Drug Center provides a comprehensive view of available drug information on the potential side effects when taking this medication. This is not a complete list of side effects and others may occur. I've been taking it for more years than I can remember. I have never noticed any side effects. It will increase you metabolism, make you feel like its not cold all the time, your appetite will increase a little, but all in all, you will feel like a normal person The information is not intended to cover all possible uses, directions, precautions, drug interactions or adverse effects, nor should it be construed to indicate that use of a particular drug is. Overall functionality should be improved as a result of taking synthroid – not further impaired. Remember that while your doctor prescribed this medication because he/she believes the benefits are likely to outweigh the side effects – not everyone responds favorably to this treatment. It is ultimately a personal decision as to whether you’d like to continue taking synthroid, switch to. The thing is, it will take a while for you to feel the effects of not taking it. So that means even when you are taking it like you should it will take you a while to feel better. the best thing would be to try and take it everyday. I don't know when you started, but you should have your levels checked about 3 months from the time you began to take it. Understanding possible side effects. Certain side effects can occur with Synthroid, and these are often the result of your body getting too much medicine, also known as overtreatment. Taking Synthroid replaces the hormones that your thyroid should be making but, for whatever reason, isn't. Like any medication, Synthroid can have side effects, but for most people, the drug. Although not all of these side effects may occur, if they do occur they may need medical attention. Check with your doctor immediately if any of the following side effects occur while taking levothyroxine: How to use Synthroid. Read the Patient Information Leaflet if available from your pharmacist before you start taking levothyroxine and each time you get a refill.