Levoxyl

( Levothyroxine Sodium )

Medically Reviewed by Dr. Harshi Dhingra, M.D.

Last Reviewed: Jul 08, 2022

Warnings

What are the risks of taking Levoxyl?

Levoxyl may not be safe for everyone and can cause serious health problems, especially in certain high-risk groups.

Not For Weight Loss: Thyroid hormones, including Levoxyl, should not be used to treat obesity or for weight loss as primary or adjunctive therapy (alone or in combination with other medications). In euthyroid individuals (people with normal thyroid function), Levoxyl is ineffective for treating obesity or for weight loss when used at the usual doses. Larger doses of Levoxyl can cause serious threatening manifestations of toxicity, including even life-threatening manifestations.
Decreased Bone Mineral Density: Taking Levoxyl (levothyroxine sodium) tablets or capsules long-term can lower your bone mineral density and weaken your bones over time, putting you at risk of bone fractures. This risk is especially high in postmenopausal women who take Levoxyl at larger doses or for a long time. It is recommended that patients should receive the minimum dose of Levoxyl (levothyroxine sodium) to achieve the desired effect. It’s important, therefore, to keep all your appointments with your doctor. They will monitor your thyroid hormone levels and give you the smallest dose of Levoxyl to keep your thyroid levels in the normal range.
Effects on the Heart: Levoxyl (levothyroxine) therapy can cause heart problems, especially when used at larger doses. The risk is higher in older individuals (age 65+) and people with underlying cardiovascular disease (coronary artery disease, coronary insufficiency, or cardiac failure). In patients with underlying cardiovascular disease, Levoxyl therapy may need to be started at a lower dose. You should contact your doctor or seek emergency medical attention if you experience chest pain, irregular or rapid heartbeat, or shortness of breath while taking Levoxyl. You may need to stop taking Levoxyl for about a week and restart the medication at a lower dose if there are cardiovascular symptoms.
Nontoxic Diffuse Goiter or Nodular Thyroid Disease : Levoxyl should be administered with caution in patients with nontoxic diffuse goiter or nodular thyroid disease, as it can lead to a serious condition called thyrotoxicosis, a condition in which there is too much thyroid hormone in the body. Call your doctor right away if you experience signs and symptoms such as rapid or irregular heartbeat, unexplained weight loss, muscle weakness, shakiness, anxiety, irritability, or nervousness while taking Levoxyl.
Associated Endocrine Disorders: Some people can have hypothyroidism and concomitant adrenal insufficiency (low adrenal hormones and low thyroid hormones). In such individuals, adrenal insufficiency needs to be treated by replacement with glucocorticoids before starting thyroid hormone treatment with Levoxyl. Levoxyl therapy in people with uncorrected adrenal insufficiency can precipitate an acute adrenal crisis in which the adrenal hormone levels fall even further. Symptoms of an acute adrenal crisis include high fever, dizziness, dehydration, stomach pain, nausea, and vomiting. Your doctor will likely check adrenal hormone levels before prescribing Levoxyl to make sure you are not at risk.
Dose Adjustments in Patients with Diabetes: Patients with diabetes may require an upward adjustment of their diabetes medications while being treated with levothyroxine (Levoxyl). Make sure you keep an eye on your blood sugar levels. Keep all your doctors’ appointments for adjustments in levothyroxine dose.

What should I tell my doctor before starting Levoxyl?

Tell your doctor if you are allergic to Levoxyl, levothyroxine sodium, thyroid supplements, or other drugs. Your pharmacy can give you a list of the active or inactive ingredients in Levoxyl tablets and capsules.

Give your doctor a complete list of your prescription and over-the-counter medications, including vitamins, nutritional supplements, and herbal products. This can help avoid serious drug interactions.

Tell your doctor about all your medical conditions. In particular, mention if you have adrenal insufficiency (a condition in which the adrenal glands do not produce enough adrenal hormones). If so, your doctor may decide not to give you Levoxyl.

Also, tell your doctor if you have diabetes, atherosclerosis (hardening of the arteries), anemia, bleeding problems, osteoporosis (weak or brittle bones), porphyria, or problems related to the pituitary gland or kidney disease, liver disease, or heart disease. Also, inform your doctor if you have recently received radiation therapy.

Tell your doctor if you are pregnant, could be pregnant, plan to become pregnant, or are breastfeeding.

What precautions should I take while on Levoxyl?

Keep all your doctors’ appointments while on Levoxyl treatment. Your doctor will check a serum TSH level and make levothyroxine dose adjustments based on the result. They will also monitor you carefully for Levoxyl side effects. You should know that it can take several weeks to notice an improvement in your symptoms, especially if you have severe or prolonged hypothyroidism. Do not stop taking Levoxyl without talking to your doctor first.

Certain foods and beverages can affect thyroid hormone pharmacokinetics, i.e., how Levoxyl works. This includes walnuts, soybeans, dietary fiber, grapefruit, and grapefruit juice. Talk to your doctor about eating or drinking these foods and beverages while on Levoxyl treatment.

If you are on ferrous sulfate (iron supplement) or calcium carbonate (Tums), take your thyroid hormone therapy prior or after (at least 4 hours away) from these medications.

If you take cholesterol-lowering medications such as cholestyramine (Prevalite), colestipol (Colestid), or colesevelam (Welchol), or medications such as sodium polystyrene sulfonate (Kayexalate) and sevelamer (Renvela, Renagel), be sure to take them at least 4 hours after your Levoxyl dose.

If you become pregnant while on Levoxyl, immediately contact your doctor with your pre-pregnancy dose. Your dose may need to be adjusted for adequate levothyroxine treatment. (The apparent adequate replacement dose is usually higher during pregnancy).

If you are having surgery, including dental surgery, tell your doctors, surgeons, and dentist that you take Levoxyl.

What are Levoxyl interactions?

Taking Levoxyl with certain other medications can affect how well this medicine works. Drug interactions can also increase the risk of serious adverse effects. Your physician may choose a different medication for hypothyroidism, change the dose or frequency of your medicines, and/or monitor you carefully for side effects if there are known interactions between Levoxyl and any other medicines.

There can be interactions between Levoxyl and the following medications:

Heart medications like amiodarone (Nexterone, Pacerone) and digoxin (Lanoxin)
Water pills such as furosemide (Lasix)
Androgens like testosterone (Androderm) and nandrolone
Certain antacids that contain aluminum or magnesium (Mylanta, Maalox, others)
Anticoagulants or blood thinners like such as heparin or warfarin (Coumadin, Jantoven)
Beta-blockers like propranolol (Inderal, Innopran), metoprolol (Lopressor), and timolol
Cancer medications like asparaginase, fluorouracil, mitotane (Lysodren), and tyrosine kinase inhibitors such as imatinib (Gleevac) or cabozantinib (Cometriq)
Antiepileptic drugs such as carbamazepine (Tegretol), phenobarbital, phenytoin (Dilantin, Phenytek)
Clofibrate (Atromid)
Corticosteroids like dexamethasone
Cough and cold medications
Weight loss medications such as orlistat (Alli, Xenical)
Hormone replacement medications and estrogen-containing oral contraceptives (birth control pills), rings, patches, injections, or implants
Breast cancer medications like tamoxifen (Soltamox)
Insulin or other medications to treat diabetes
Proton pump inhibitors such as lansoprazole (Prevacid), esomeprazole (Nexium), and omeprazole (Prilosec)
Certain antidepressants like sertraline (Zoloft), amitriptyline (Elavil), and maprotiline (Ludiomil)
NSAIDs (painkillers) such as mefenamic acid (Ponstel)
Opioid drugs such as methadone (Methadose)
B vitamins such as niacin
Anti-gas medications like simethicone (Phazyme, Gas X)
Anti-tuberculosis drugs like rifampin (Rifater, Rifamate, Rifadin)
Anti-ulcer medications like sucralfate (Carafate)

This is not a complete list of Levoxyl drug interactions. Be sure to give your doctor a complete list of the medications you are taking or plan to take, even if they do not appear on this list.

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