Synthroid Side Effects: Synthroid is a brand of levothyroxine key used primarily for replacement of thyroid hormone in patients with hypothyroidism. The most common Synthroid side effects are related to over treatment or misuse of Synthroid. Synthroid is synthetically produced exact replica of the polypeptide levothyroxine produced by the human thyroid gland and so when used in ideal dosage there are usually few if any Synthroid side effects.
Black Box Warning: Synthroid is not FDA approved for treatment of obesity or for weight loss therapy and should not be used for this indication. Synthroid only would be effective in accomplishing weight loss in doses larger than naturally occur in a euthyroid (normal thyroid levels) person and can lead to be serious and even life-threatening toxicity especially when used in combination with sympathomimetic appetite suppressants.
Common Synthroid Side Effects: Most of the common Synthroid side effects are related to episodes of use of doses of Synthroid that cause a pharmacologic hyperthyroidism. These include symptoms are typical of hyperthyroidism like palpitations and tachycardia, tremor, nervousness, nausea, anxiety, diarrhea and weight loss, Donald cramps, and he intolerance. Other common symptoms of over treatment with Synthroid include hair loss, menstrual irregularities, difficulty sleeping, sweating and increased appetite.
Serious Synthroid Side Effects: As with the common Synthroid side effects serious Synthroid side effects also often relate to overuse of the medication and especially with long-term overuse can cause congestive heart failure, cardiac arrhythmias, high blood pressure, chest pain from coronary artery disease, and seizures. Synthroid is used in pediatric patients with congenital hypothyroidism and potential serious Synthroid side effects in these infants can be pseudotumor cerebri, craniosynostosis and premature closure of the skull bone growth plates.
Cautions, contraindications, and drug interactions: Synthroid is contraindicated or needs to be used with extreme caution is in several situations where cardiovascular system may be unstable including in the case of acute myocardial infarction, adrenal insufficiency prior to corticosteroid therapy, in other types of unstable cardiovascular disease, and in the very elderly patient. When there is pre-existing suppression of endogenous TSH uses Synthroid should be questioned. In diabetes mellitus uses Synthroid is frequently made needed but needs to be done with caution. Of course adding additional thyroid function with Synthroid is contraindicated in thyrotoxicosis, condition of severe hyperthyroidism.
One herbal supplement called lemon balm is contraindicated for use with Synthroid. Careful monitoring or modification of therapy may be needed in a large number of medications of which only a few of the more common will be mentioned here. Patients should consult with their physician or pharmacist regarding specific medication interaction concerns and refer to the manufacturers prescribing guidelines for complete list of potential drug interactions or situations where careful monitoring or modification of therapy may be needed. Numerous medications can interfere with the absorption of Synthroid including antacids, bile acid binding resins, calcium salts, some types of iron supplementation, sucralfate, and some high calcium foods. Numerous medications may alter levothyroxine levels in Synthroid therapy including amiodarone, barbiturates, carbamazepine, phenytoin, rifampin, and red yeast rice. Treatment with Synthroid may alter blood levels or efficacy of numerous medications including theophylline, several oral hyperglycemic including its the sulfonylureas, and of special importance warfarin.
Pregnancy and Lactation: Synthroid is considered pregnancy category A and is considered safe for use during lactation. This makes sense because it is chemically exactly the same as the naturally occurring levothyroxine produced but human thyroid.
Pharmacology: the serum half-life of levothyroxine in euthyroid patients in steady-state is approximately 6 to 7 days. Half-life may be longer in hypothyroid patients and somewhat shorter in hyperthyroid patients. Levothyroxine is primarily metabolized in the liver although some metabolism by kidney tissue or excretion unchanged in the urine probably occurs.
Synthroid has a reputation as a high quality levothyroxine product. Some years ago there were comparisons of consistency of serum T for levels after generic levothyroxine versus Synthroid and some evidence may have suggested that Synthroid was superior. In recent years this is been questioned and most physicians prescribe generic levothyroxine at this point leading to considerable cost savings.
In humans the functioning thyroid hormone is a balance between two types of thyroid hormone commonly called T4 and T3 as acronyms for levothyroxine and triiodothyronine. Synthroid is a synthetically produced T4. For patients on therapy with levothyroxine 25 µg of levothyroxine is approximately equal to 100 µg of levothyroxine which is approximately equal to one grain of USP thyroid. Additionally some natural paths prefer treatment with USP thyroid or a brand of USB thyroid called Armour Thyroid. This is actually thyroid hormone obtained from pigs thyroid which is ground up and 80 been formulated into pills. Most medical physicians feel that there is little veracity to the method that patients feel or do better on porcine thyroid than on human thyroid replacement.
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The information on this site is provided solely as a supplement to the advice, expertise, judgement and care of your healthcare professional. This content is not intended to be comprehensive, and is purposefully limited to what are felt to be some of the relevant and helpful side effect issues that the medication discussed may be associated with in a given individual. Nothing written at SideEffectz.com is to be interpreted as implying that a medication is safe, is appropriate for any given individual, or will or even may be effective for a given individual. It is very important that you consult with your healthcare professional prior to using any drug or supplement, or prior to stopping or starting any type of medical treatment.