1. I know one of the symptoms of hypothyroid is having cold arms and feet. Does having "cold" arms and feet literally means being cold of all the arms and feet? If so, then why do I have only the hands and feet being cold?
This can be one of the symptoms of hypothyroidism; not everyone experiences it. If you stop and think about it, the hands and feet are the farthest points from the heart. If your heart is pumping slowly because you're hypothyroid, it's harder to get the blood to them and so they may feel cold.
2. I was prescribed 25mcg of Thyrax, and I was going to take every morning. What are the side effects of this drug?
Thyrax is a brand name for the drug Levothyroxine, the most commonly prescribed medication for hypothyroidism. It really has no side effects generally. It sometimes does take time, though, to get the proper balance of hormones in your body. It may take about six weeks for you to feel the full effects of the medication. Adjustments in the dosage of medication may need to be made to get to just the right dose for you. Be sure to follow up with your doctor on this.
3. And how long do I have to take this medication to cure my hypothyroidism? Is it gonna last for life?
Hypothyroidism is nearly alway a chronic condition. The medication you're taking is not a cure for the condition, but a replacement of the hormone your body is missing because the thyroid gland isn't working right. In that way, it's somewhat like diabetes, where the body isn't producing enough insulin so supplimentation is needed.
Take your medication every morning, follow up with your doctor and you should be completely healthy and able to do everything a healthy person does.