Thyroxine is the key hormone secreted by follicular cells of the thyroid gland into the bloodstream. It is secreted in its inactive form and is converted to its active form by organs like the liver and kidneys. The active form of thyroxine is triiodothyronine. Thyroid hormones help in regulations of body’s metabolic rate, muscle control, digestive and heart functions, maintenance of bones and 
brain development. Levothyroxine or rather L-thyroxine is a synthetically made thyroid hormone which is chemically similar to the naturally secreted thyroxine in every aspect. The synthetic hormone is used in treatment of Thyroid hormone deficiency and it further prevents the recurrence of thyroid cancer. Thyroxine side effects due to Levothyroxine therapy results from dosing and interactions.
Levothyroxine
Levothyroxine has a myriad of side effects and it can interfere with most medications. Not all the side effects of levothyroxine are serious as some are due to body adjustment to therapeutic treatment. The less serious side effects fade away with time and they do not require immediate medical attention. Health care professionals can help with ways of reducing or even preventing the expected side effects. If any side effects are really bothersome or rather continuous, immediate medical attention should be sought. The serious side effects which require emergency medical help includes: swelling of face, tongue, lips or tongue; difficulty in breathing and hives. The serious side effects are signs of body’s allergic reaction towards the drug and medical action need be taken immediately. Though allergic reactions to this drug are unlikely, any symptom close to constant occurring body rash, itching, dizziness, rapid pulse, irregular heart beat and troublesome breathing should be reported.
Common Side Effects
Most common side effects of Levothyroxine exist. Prescription of this drug as medication is after keen consideration of its benefits and side effects. Doctors make the decision of prescribing the medication after judging that the benefits are greater than the risk of serious side effects. Common side effects include: Diarrhea, nausea, stomach cramps, nervousness, vomiting, angina- chest pains as heart does not receive adequate blood, tremors, restlessness, irritability and excitability, increased appetite, difficulty in sleeping, headache, hot flushes, excessive sweating, intolerance to heat, slight weight loss, muscle cramps, menstrual irregularities, increased bowel frequency, anxiety, muscular weakness and partial hair loss especially in children in the early months of medication. These side effects do occur but if they persist you should inform your doctor for immediate medical attention.
Rare Side Effects
Rare side effects which have been reported do exist. The side effects are least expected and should be reported if they persist. The side effects includes: dizziness, eye pain, blurred or double vision, retarded growth in children, limping or walk that favours one leg, pains in the knee or hip region, seizures and severe headaches. Furthermore, decreased urine output, difficulty with swallowing, dilated neck veins, extreme fatigue and fainting have been reported. Levothyroxine has a long half-life hence its effects may not exist for long after initiation of therapy or as dosage increases.
Cardiovascular Side Effects
Cardiovascular side effects include symptoms of hypertension, tachycardia, palpitations and angina. The side effects are usually exacerbated in hospital patients with profound cardiovascular disorders. In addition, Ischemic heart disease and effects on normal cardiac functions includes: elevated left ventricle mass index, increased left ventricular systolic activity and increase in incidences of irregular heart beats. Endocrine side effects includes alterations in symptom presentation for both adrenal cortical insufficiency and diabetes. Nervous system side effects rarely include seizures when initiating therapy. Dermatological side effects which includes transient hair loss have been experienced during initial months of therapy. Musculoskeletal side effects includes the elevated risk of osteoporosis. Levothyroxine is well tolerated by the body. Thyroxine side effects which are associated with levothyroxine medication results from overdose or the symptoms of congenital hyperthyroidism.