Basically anything that can occur when thyroid hormone levels are low can happen. This includes but is not limited to:

Depression
Fatigue
Dry skin
Coarse hair
Weight gain
Feeling cold

Thyroid hormone is one of the most important hormones in the body because it basically controls the other hormones. I would not suggest stopping it. Please google the following TSH or T4 and read about the power of the thyroid on the human body.