Monday, February 26, 2024

Side Effects Of Synthroid Thyroid Medicine

Enhancing Healthcare Team Outcomes

How to take Levothyroxine (Synthroid) Correctly | Side Effects All Patients Need to Know

Upon first prescribing levothyroxine, medication adjustment should occur every 6 to 8 weeks until the patient reaches a steady state. Clinicians should also evaluate the response to levothyroxine by using a validated questionnaire, such as thyroid-related quality of life and the underactive thyroid treatment satisfaction questionnaire . If the patient has symptoms of hyperthyroidism, advise the patient to contact the clinician to determine if these are side effects of the medication. A clinician should then order TSH and free T4 levels immediately. If the free T4 comes back elevated, the clinician should decrease the dose of levothyroxine to prevent cardiac complications and other symptoms of hyperthyroidism. Finally, clinicians should refer the patient to an endocrinologist if hypothyroidism is due to central causes. In all the scenarios mentioned above, pharmacists should ensure proper dosing and report to the clinician if there is any potential drug-drug interaction or if supplies may dictate a change to a different formulation.

What Should I Avoid While Taking Levothyroxine

Levothyroxine is generally well tolerated as the third-most prescribed drug in the U.S. in 2020. Certain supplements or foods containing fiber, calcium, or iron taken with the tablet form of levothyroxine can reduce its effectiveness, according to a review of 63 studies published in the journal Pharmaceuticals in 2021. Coffee and other caffeinated drinks may also inhibit absorption of levothyroxine, which is why doctors recommend taking it at least 30 to 60 minutes before eating breakfast. If levothyroxine causes gastrointestinal issues on an empty stomach, a gel capsule or liquid with meals may be more easily tolerated.

Hormone therapies including birth control pills, estrogen, or testosterone may require a change in the dosage of levothyroxine.

Thyroid Hormone Replacement Drugs

Levothyroxine is a type of thyroid hormone replacement drug that is often used to treat hypothyroidism. Brand names for levothyroxine include Synthroid, Levoxyl, and Tirosint.

Natural desiccated thyroid is also used to treat hypothyroidism. For some people, NDTs work better than levothyroxine. Many people prefer NDTs because they are considered more natural. Brand names NDTs include Armour and Nature-Throid.

Usually, people start thyroid hormone therapy by taking a low dose and gradually increasing it. Since hypothyroidism progresses over time, starting therapy with a low dose is helpful for reducing the risk of overmedication.

If you’re prescribed levothyroxine, your provider will tell you how much to take. Still, it’s possible to take too much levothyroxine by accident.

  • Feeling like your heart is skipping a beat or racing
  • Weight loss with no change in your diet or exercise routine
  • Increase in food intake with no weight gain

In some cases, the symptoms and side effects of taking too much levothyroxine are similar to those of hypothyroidism. For example, you may feel more exhausted than usual, feel achy , or feel jittery and anxious. You may also gain weight.

It’s not unheard of for a person to go to their healthcare provider because they think they need a higher dose of their medication only to find out their symptoms are actually being caused by thyroid overmedication.

Thyroid Disease Healthcare Provider Discussion Guide

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How Should This Medicine Be Used

Levothyroxine comes as a tablet and a capsule to take by mouth. It usually is taken once a day on an empty stomach, 30 minutes to 1 hour before breakfast. Follow the directions on your prescription label carefully, and ask your doctor or pharmacist to explain any part you do not understand. Take levothyroxine exactly as directed. Do not take more or less of it or take it more often than prescribed by your doctor.

Swallow capsules whole do not chew or crush them. Do not remove the capsule from the package until you are ready to take it.

Take the tablets with a full glass of water as they may get stuck in your throat or cause choking or gagging.

If you are giving levothyroxine to an infant, child, or adult who cannot swallow the tablet, crush and mix it in 1 to 2 teaspoons of water. Only mix the crushed tablets with water do not mix it with food or soybean infant formula. Give this mixture by spoon or dropper right away. Do not store it for later use.

Your doctor will probably start you on a low dose of levothyroxine and gradually increase your dose.

Levothyroxine controls hypothyroidism but does not cure it. It may take several weeks before you notice a change in your symptoms. Continue to take levothyroxine even if you feel well. Do not stop taking levothyroxine without talking to your doctor.

What Are The Long

Thyroid Levothyroxine Side Effects

Synthroid is considered a safe and effective therapy. It can take some trial and error to find the correct dose. Eventually, you and your healthcare provider will settle on an adequate amount for the long haul. People take these medicines for decadesusually for a lifetime.

Because of this, its a good idea to confirm with your healthcare provider that youre on the right amount of thyroid hormone. Ideally, you should be on the lowest possible dose to control your thyroid deficiency. Thats why healthcare providers often start low and then slowly increase your dose, depending on your response .

There are two potential side effects from long-term use that you may want to discuss with your healthcare provider: bone-thinning and heart-related issues.

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What Should I Know About Storage And Disposal Of This Medication

Keep this medication in the container it came in, tightly closed, and out of reach of children. Store it at room temperature and away from excess heat and moisture .

It is important to keep all medication out of sight and reach of children as many containers are not child-resistant and young children can open them easily. To protect young children from poisoning, always lock safety caps and immediately place the medication in a safe location â one that is up and away and out of their sight and reach.

Unneeded medications should be disposed of in special ways to ensure that pets, children, and other people cannot consume them. However, you should not flush this medication down the toilet. Instead, the best way to dispose of your medication is through a medicine take-back program. Talk to your pharmacist or contact your local garbage/recycling department to learn about take-back programs in your community. See the FDA’s Safe Disposal of Medicines website for more information if you do not have access to a take-back program.

What Are The Short

As you and your healthcare provider look for the correct dose of Synthroid or levothyroxine, you may experience side effects. These usually stem from the dosage not being quite right. If youre on a dose thats too low, you may experience the same symptoms you were feeling with your hypothyroidism. Inform your healthcare provider if you have any other medical conditions or take other medications to avoid potential drug interactions.

You can also experience some side effects if youre getting too much thyroid hormone. If your Synthroid dose is too high, it can lead to a condition known as hyperthyroidism.

Be sure to seek medical advice if you experience any of the following side effects so that dose adjustments can be made :

  • Fast or abnormal heart rate

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The goal of Synthroid is to restore your T4 and TSH to normal levels by supplying your body with a synthetic version of the same hormone. Ideally, the correct dose of Synthroid mimics normal thyroid function.

It takes approximately four to eight weeks to start feeling better on Synthroid . Your healthcare provider will check your TSH blood test about six weeks after starting you on the medicine. If your thyroid hormone levels have returned to normal, that means youre taking the right amount of Synthroid.

Synthroid is usually taken once a day, ideally on an empty stomach. To maximize effectiveness, avoid taking it with prescription or over-the-counter antacids.

Before Taking This Medicine

Synthroid Side Effects EXPLAINED (Including Hair Loss, Weight Gain, Depression & More)

Synthroid should not be used to treat obesity or weight problems. Dangerous side effects or death can occur from the misuse of levothyroxine, especially if you are taking any other weight-loss medications or appetite suppressants.

Since thyroid hormone occurs naturally in the body, almost anyone can take levothyroxine. However, you may not be able to take this medicine if you have certain medical conditions. Tell your doctor if you have:

  • an untreated or uncontrolled adrenal gland disorder

  • a thyroid disorder called thyrotoxicosis or

  • symptoms of a heart attack .

To make sure Synthroid is safe for you, tell your doctor if you have ever had:

  • a thyroid nodule

  • heart disease, a blood clot, or a blood-clotting disorder

  • kidney disease

  • osteoporosis, or low bone mineral density

  • problems with your pituitary gland or

  • any food or drug allergies.

Tell your doctor if you have recently received radiation therapy with iodine .

If you become pregnant while taking Synthroid, do not stop taking the medicine without your doctor’s advice. Having low thyroid hormone levels during pregnancy could harm both mother and baby. Your dose needs may be different during pregnancy.

Tell your doctor if you are breast-feeding. Your dose needs may be different while you are nursing.

Do not give this medicine to a child without medical advice.

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What Other Drugs Will Affect Synthroid

Many other medicines can be affected by your thyroid hormone levels. Certain other medicines may also increase or decrease the effects of Synthroid.

Certain medicines can make levothyroxine less effective if taken at the same time. If you use any of the following drugs, avoid taking them within 4 hours before or 4 hours after you take Synthroid:

Side Effects Of Levothyroxine

As with any drug, there is a risk of side effects when taking levothyroxine. It should be noted, however, that side effects with levothyroxine are usually related to the dose being too high or too low. When the dose is correct, it is unlikely to have any side effects as you are replacing a hormone your body would be naturally making.

The most common side effects associated with levothyroxine include:

  • Pain or discomfort in the chest

  • Swelling of hands or feet

Let your health care provider know if you experience any side effects, especially if they are persistent or severe. The side effects of levothyroxine are often linked to taking a higher dosage than necessary. Lowering your dose may help reduce side effects.

Seek emergency care if you have trouble breathing or experience swelling of your face, lips, throat, or tongue, which could indicate an allergic reaction.

Most adults and children tolerate levothyroxine well, and it can be taken with most other medications. Some people should not take levothyroxine, including those with adrenal conditions, high blood pressure, hyperthyroidism, heart disease, or people who are allergic to the drug.

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What Drugs Interact With Synthroid

Drugs Known To Affect Thyroid Hormone Pharmacokinetics

Many drugs can exert effects on thyroid hormone pharmacokinetics and metabolism and may alter the therapeutic response to Synthroid .

Table 2: Drugs That May Decrease T4 Absorption

Potential impact: Concurrent use may reduce the efficacy of Synthroid by binding and delaying or preventing absorption, potentially resulting in hypothyroidism.
Drug or Drug Class
Monitor patients treated concomitantly with orlistat and Synthroid for changes in thyroid function.
Bile Acid Sequestrants Ion Exchange Resins Bile acid sequestrants and ion exchange resins are known to decrease levothyroxine absorption. Administer Synthroid at least 4 hours prior to these drugs or monitor TSH levels.
Proton Pump Inhibitors Sucralfate Antacids Gastric acidity is an essential requirement for adequate absorption of levothyroxine. Sucralfate, antacids and proton pump inhibitors may cause hypochlorhydria, affect intragastric pH, and reduce levothyroxine absorption. Monitor patients appropriately.

Table 3: Drugs That May Alter T4 and Triiodothyronine Serum Transport Without Affecting Free Thyroxine Concentration

Table 4: Drugs That May Alter Hepatic Metabolism of T4

Table 5: Drugs That MayDecrease Conversion of T4 to T3

Antidiabetic Therapy

Oral Anticoagulants

Digitalis Glycosides

Antidepressant Therapy



Tyrosine-Kinase Inhibitors

Drug-Food Interactions

Drug-Laboratory Test Interactions

What Are The Dosages Of Levothyroxine

Synthroid (Levothyroxine) Side Effects &  Adverse Reactions

Dosages of Levothyroxine Should Be Given As Follows:

Adult and Pediatric Dosage Forms & Strengths

Tablet form of medication

  • 25 mcg, 50 mcg, 75 mcg, 88 mcg, 100 mcg, 112 mcg
  • 25 mcg, 137 mcg, 150 mcg, 175 mcg, 200 mcg, 300 mcg

Capsule form of medication

  • 13 mcg, 25 mcg, 50 mcg, 75 mcg, 88 mcg
  • 100 mcg, 112 mcg, 125 mcg, 137 mcg, 150 mcg

Powder for injection form of medication

  • 1.7 mcg/kg or 100-125 mcg PO qDay not to exceed 300 mcg/day
  • Usual initial drug dose: 25-50 mcg/day
  • May adjust drug dose by 12.5-25 mcg q6-8Week
  • > 50 yr with CV disease
  • Usual initial drug dose: 12.5-25 mcg PO qDay
  • May adjust drug dose by 12.5-25 mcg q4-6weeks until patient becomes euthyroid and serum TSH concentration normalized adjustments q6-8weeks also used
  • Dose range: 100-125 mcg PO qDay
  • Severe Hypothyroidism

    Initial drug dose: 12.5-25 mcg PO qDay

    Adjust drug dose by 25 mcg/day q2-4Week PRN

    Subclinical Hypothyroidism

    • Initial: 1 mcg/kg PO qDay may be adequate, OR
    • If replacement therapy not initiated, monitor patient annually for clinical status

    Myxedema Coma

    • 300-500 mcg IV once, THEN 50-100 mcg qDay until patient is able to tolerate oral administration may consider smaller doses in patients with cardiovascular disease

    Dosing ConsiderationsMonitoring

    • Initially evaluate patients every 6-8 weeks
    • Once normalization of thyroid function and serum TSH concentration achieved, evaluate every six to 12 months.


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    You Don’t Feel Any Better

    Thyroid medications usually do not work right away. It can take a few days to a few weeks for you to even start noticing a difference in how you feel. If you don’t feel better after taking your medication for several months, you may need a dose adjustment or a different medicationnot a complete stop of your regimen.

    How Should I Take It

    Armour Thyroid is typically taken orally once daily. The dosage requirements are usually individualized based on patient needs. Dosage is usually low at the beginning of treatment so that your body can become accustomed to it.

    If youve accidentally missed a pill, do not take two pills at once. Just continue with your medication normally.

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    Common Side Effects Of Synthroid

    As with any medication, Synthroid can cause some very common, non-serious side effects. Many side effects of Synthroid are self-limiting . If any of the following adverse effects become bothersome, notify your healthcare provider.

    • Heart palpitations and tachycardia
    • Increased nervousness, anxiety, and tremor
    • Increased appetite

    Should You Be Taking Thyroid Medication

    Thyroid and Anti-Thyroid Medications – Pharmacology – Endocrine System | @LevelUpRN

    So how do you know if you should be taking thyroid medicine? I mentioned blood work, and that really is the place to start. You need to know your baseline before taking any steps to address the symptoms that are leading you to believe that you have thyroid disease.

    To determine whether or not you have optimal thyroid levels, you should be asking for blood work to look at the following information:

    • Thyroid antibodies

    In addition to blood tests, you can also ask for a thyroid ultrasound, which can identify nodules and may be used as a diagnostic predictor.

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    Which Medications Suppress Thyroid Stimulating Hormone

    1. Glucocorticosteroids.

    • Human serum TSH levels are known to be influenced by glucocorticoids.

    • With lower levels in the morning and greater levels at night, physiological levels of hydrocortisone are crucial in the diurnal fluctuation of serum thyroid-stimulating hormone levels.

    • It is demonstrated that hypothyroid patients and healthy individuals had serum thyroid-stimulating hormone levels lowered by large glucocorticoids. This impact, which was regulated at the hypothalamic level, appeared to be related to thyroid-stimulating hormone secretion.

    • Although other people have confirmed this effect, it does not seem like long-term high-dose glucocorticoids or Cushing’s syndrome cortisol excess induce clinically apparent central hypothyroidism that needs thyroid hormone replacement.

    • While Prednisone doses of 30 milligrams are probably necessary to meaningfully modify serum thyroid-stimulating hormone levels, Dexamethasone doses of as little as 0.5 milligrams can diminish serum thyroid-stimulating hormone levels.

    • As a result of their direct effects on TRH in the hypothalamus, Glucocorticoids can decrease blood thyroid-stimulating hormone levels and thyroid-stimulating hormone production.

    • Clinically significant central hypothyroidism is not caused by chronic high doses of Glucocorticoids or severe Cushing’s syndrome.

    2. Dopamine or Bromocriptine.

    3. Somatostatin Analogues.

    4. Retinoids.

    5. Other Drugs That Might Influence TSH Levels.


    When To See A Healthcare Provider

    Contact your healthcare provider if you’re experiencing symptoms of too much levothyroxine. They can do tests to check your thyroid levels and figure out if youre being overmedicated.

    If your provider determines that you are taking too much levothyroxine, they will reassess your treatment plan. They might advise you to change your diet if it’s contributing to thyroid overmedication. Your provider might also change your medication or adjust your dose.

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    It’s Difficult To Remember To Take Your Dose

    There are a number of strategies you can use to remember to take your thyroid medication. Your phone, computer, or another alarm can be programmed to give you a daily reminder. You can keep your medicine in an obvious place, such as your bedroom or kitchen, or you can use a pill organizer to keep you on track.

    How The Thyroid Gland Works

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    Think of the thyroid as your bodys internal thermostat. This small bow-tie shaped gland is a power player in the body, one that has the potential to inflict a lot of chaos and confusion. It regulates your heart rate, metabolism, gastrointestinal function, menstrual cycle, mood, respiration and virtually every other function in the body.

    When your body doesnt make enough thyroid hormone, everything slows down, and you develop hypothyroidism. Symptoms vary. Some people gain weight, suffer depression or develop dry skin and nails. Others experience constipation, a foggy brain and chronic fatigue. Women may notice that their periods are heavier and more frequent, and that it may be difficult to get pregnant.

    Too much thyroid hormone causes hyperthyroidism and has the opposite effect. This condition makes you anxious and irritated, and you may lose weight, have trouble sleeping and suffer diarrhea. It can also cause heart palpitations and weak bones. Hyperthyroidism is much less common than hypothyroidism and affects only about 1% of the population.

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