[EllaC]

Major Side Effects
You should check with your doctor immediately if any of these side effects occur when taking levothyroxine:

Less common:
Chest pain or discomfort
decreased urine output
difficult or labored breathing
difficulty with swallowing
dilated neck veins
extreme fatigue
fainting
fast, slow, irregular, pounding, or racing heartbeat or pulse
fever
heat intolerance
hives or welts
increased blood pressure
increased pulse
irregular breathing
irritability
menstrual changes
nausea
pain or discomfort in the arms, jaw, back, or neck
shortness of breath
skin itching, rash, or redness
sweating
swelling of the eyes, face, lips, throat, or tongue
tightness in the chest
tremors
troubled breathing