Levothyroxine is the generic name of a drug prescribed in the treatment of hypothyroidism, goiters and thyroid cancer. It is sold under such brand names as Unithroid, Levothroid, Synthroid and Levoxyl. Hypothyroidism sufferers have a condition in which a gland called the thyroid fails to produce the correct amount of the thyroid hormone. Levothyroxine is administered as a pill.
Serious Side Effects
Serious side effects produced by levothyroxine may need medical treatment, so call your doctor immediately if you get any of them. Less common serious side effects, states the Mayo Clinic, may include diplopia or double vision, a retardation of child growth, appetite changes, irritability, discomfort or pain in the chest, breathing that is irregular, bone mineral density decreases, joint inflammation, lowered output of urine, pulse increases, diarrhea and welts or hives. Others may include breathing problems, nausea, bodily motion problems, stiffness or pain in the muscles, swallowing difficulties, abnormal liver function, dilated neck veins, menstrual cycle changes, eye pain, extreme fatigue, swollen patches on the genitals, face, feet, eyelids, legs, in the throat, on the tongue or hands or on the face. You also may experience a fever, tachycardia (rapid heartbeat), bradycardia (reduced heartbeat) or arrhythmia (irregular heartbeat), shortness of breath, severe headaches, irregular breathing, increased or decreased weight, unconsciousness, vomiting and stopping of the heart. Rarely, some people taking levothyroxine have had seizures.
Temporary Side Effects
Levothyroxine can induce some side effects at the beginning of treatment that will go away as you acclimate to it. These are categorized as less common temporary side effects and include abnormal weakness or tiredness, abdomen cramps, insomnia, crying, depersonalization, dysphoria, changing emotional moods, euphoria, fertility problems, excessive sweating, restlessness, fear, paranoia and hair loss. Others include skin redness, sensation of bodily warmth, headaches, appetite increases, depression, nervousness and muscle weakness. If any of these persist call your physician.
Overdose Side Effects
Go to the nearest emergency room if you take more than the prescribed dose of levothyroxine. The side effects of a levothyroxine overdose include sudden slurred speech, incoordination and headache, consciousness changes, clammy and cold skin, confusion, unconsciousness, disorientation, lightheadedness and a weak and fast pulse.