Understanding Possible Side Effects

If you suffer from several or more of the above symptoms and are worried that you might have a thyroid problem, your next best step would be to visit your healthcare provider to get evaluated and discuss your options. You may also find it useful to learn more about thyroid testing beforehand to help you formulate good questions to ask your provider. If you’re not feeling quite right, it’s worth taking a closer look at the symptom list below.

Clinical Pharmacology for Synthroid

Carefully monitor glycemic control after starting, changing, or discontinuing SYNTHROID see DRUG INTERACTIONS. For secondary or tertiary hypothyroidism, serum TSH is not a reliable measure of SYNTHROID dosage adequacy and should not be used to monitor therapy. Use the serum free-T4 level to titrate SYNTHROID dosing until the patient is clinically euthyroid and the serum free-T4 level is restored to the upper half of the normal range see Recommended Dosage And Titration. A case control study on 15 SCH and 15 euthyroid controls revealed significantly lower FVIII and vWF activities in SCH compared to controls, which is in favor of a bleeding tendency. However, bleeding time and PT were similar between SCH and controls (38). Fibrinogen and PAI-1 levels are significantly lower in hypothyroid patients compared to their euthyroid state after hormone replacement therapy (48).

  • Synthroid is prescribed in tablets that range from 25 to 300 mcg in strength and is usually taken once a day with a full glass of water (about 8 ounces) 30 to 60 minutes before breakfast for best adsorption into the body.
  • Dosage titration is based on serum TSH or free-T4 see Important Considerations For Dosing.
  • Rapid restoration of normal serum T4 concentrations is essential for preventing the adverse effects of congenital hypothyroidism on cognitive development as well as on overall physical growth and maturation.

Concurrent use of tricyclic (e.g., amitriptyline) or tetracyclic (e.g., maprotiline) antidepressants and SYNTHROID may increase the therapeutic and toxic effects of both drugs, possibly due to increased receptor sensitivity to catecholamines. Toxic effects may include increased risk of cardiac arrhythmias and central nervous system stimulation. Administration of sertraline in patients stabilized on SYNTHROID may result in increased SYNTHROID requirements. Addition of SYNTHROID therapy in patients with diabetes mellitus may worsen glycemic control and result in increased antidiabetic agent or insulin requirements. Carefully monitor glycemic control, especially when thyroid therapy is started, changed, or discontinued see WARNINGS AND PRECAUTIONS.

Use In Specific Populations

Thyroid hormones, including SYNTHROID, either alone or with other therapeutic agents, should not be used for the treatment of obesity or for weight loss. In euthyroid patients, doses within the range of daily hormonal requirements are ineffective for weight reduction. Larger doses may produce serious or even life-threatening manifestationsof toxicity, particularly when given in association with sympathomimetic amines such as those used for their anorectic effects. Circulating thyroid hormones are greater than 99% bound to plasma proteins, including thyroxine-binding globulin (TBG), thyroxine-binding prealbumin (TBPA), and albumin (TBA), whose capacities and affinities vary for each hormone. The higher affinity of both TBG and TBPA for T4 partially explains the higher serum levels, slower metabolic clearance, and longer half-life of T4 compared to T3. Protein-bound thyroid hormones exist in reverse equilibrium with small amounts of free hormone.

Patient Information for Synthroid

If you’ve got a rash, fever, exhaustion, or hives, call your doctor immediately, she says. They can switch you to a different type of generic or tell the pharmacy you need to be on the brand name. Always consult your healthcare provider to ensure the information displayed on this page applies to your personal circumstances.

That said, many women find their chronic headaches improve once the Synthroid kicks in. Although there are about 1 percent of patients that won’t respond to Synthroid at all and will need other treatment, the vast majority of people on it feel remarkably better within six weeks of starting it, she adds. Along with its needed effects, levothyroxine (the active ingredient contained in Synthroid) may cause some unwanted effects.

  • Elevated TAFI antigen levels were detected in overt hypothyroidism, suggesting fibrinolysis inhibition and levothyroxine treatment was effective in reducing these levels (65-67).
  • Although not all of these side effects may occur, if they do occur they may need medical attention.
  • In pregnant patients with primary hypothyroidism, maintain serum TSH in the trimester-specific reference range.

One sign that you’ve entered into hyperthyroid territory is a racing or irregular heart rate. If you’re having any heart issues at all, it’s important to call your doctor right away. They may or may not be related to your medications but you should get it checked out either way, she says. Like any medication, Synthroid can have side effects, but for most people, the drug just makes them feel awesome again, Goldfarb says.

  • If cardiac symptoms develop or worsen, reduce the SYNTHROID dose or withhold for one week and restart at a lower dose.
  • Persistent clinical and laboratory evidence of hypothyroidism despite an apparent adequate replacement dose of SYNTHROID may be evidence of inadequate absorption, poor compliance, drug interactions, or a combination of these factors.
  • You are encouraged to report negative side effects of prescription drugs to the FDA.

Our Synthroid Side Effects Drug Center provides a comprehensive view of available drug information on the potential side effects when taking this medication. This document does not contain all possible side effects and others may occur. Check with your physician for additional information about side effects. Get medical help right away, if you have any of the symptoms listed above.

Although not all of these side effects may occur, if they do occur they may need medical attention. In contrast to the comments noted above, there are several studies that are in favor of a hypercoagulable state or a “No change” in hemostasis parameters. A 26yr old man presented to haematology with a short history of easy bruising. At MedicineNet, we believe it is important to take charge of your health through measures such as a living healthy lifestyle, practicing preventative medicine, following a nutrition plan, and getting regular exercise.

Subclinical hypothyroidism and autoimmune thyroiditis (AIT) has been reported in a patient with cerebral venous thrombosis (85). This is a synthroid bladder case of acquired von Willebrand disease due to Hashimoto’s thyroiditis. It is the most common coagulopathy in hypothyroidism and is characterised clinically by easy bruising, epistaxis and mucosal bleeding and biochemically through elevated APTT, reduced Factor VIII and von Willebrand Factor.