Generic Name: Levothyroxine

  • What is this medication and its most common uses?

    Synthroid is a medicine used to treat hypothyroidism (an underactive thyroid gland). It is also used to treat or prevent certain other thyroid conditions such as goiter (an enlarged thyroid gland); inflammation of the thyroid gland; thyroid hormone deficiency due to surgery, radiation, or certain medications; or for the management of certain thyroid cancers.

  • What should I know when beginning and continuing on this medication?

    How does this medication work?

    When you have hypothyroidism, your thyroid gland does not make enough thyroid hormone. Synthroid works by replacing your thyroid hormone, helping to restore the balance in your body.

    What are the beneficial effects of this medication and when should I begin to have results?

    What: By restoring your thyroid hormone balance, Synthroid helps to relieve your symptoms associated with low thyroid levels.

    When: It may take several weeks before you notice an improvement in your symptoms, so try to be patient and follow your healthcare provider's directions. Though you may not feel an improvement or change in the way you feel, it is very important to keep taking your medicine as prescribed to keep your condition under control.

    How do I know it is working?

    Your healthcare provider may order tests regularly to check how well this medication is working.

  • What are the possible side effects of this medication?

    The following is not a full list of side effects. Side effects cannot be anticipated. If any develop or change in intensity, tell your healthcare provider as soon as possible. Only your healthcare provider can determine if it is safe for you to continue taking this medication.

    Do not take Synthroid, either alone or in combination with other medicines, to treat obesity or for weight loss. In people with normal thyroid levels, doses of Synthroid typically used for hormone replacement are not effective for weight loss. Larger doses may result in serious or even life-threatening effects, especially when used in combination with certain other medicines used to reduce appetite.

    More common side effects may include: fatigue, changes in your mood, increased heart rate and blood pressure.

    Less common side effects may include:

    Rapid or irregular heartbeat, chest pain, shortness of breath, leg cramps, headache, nervousness, irritability, trouble sleeping, tremors, changes in your appetite, weight gain or loss, vomiting, diarrhea, excessive sweating, fever, changes in your menstrual periods, hives, or a rash.

    Weak bones (especially in women after menopause) with long-term use.

    Partial hair loss during the first few months of treatment, but this is usually temporary.

  • Who should not take this medication?

    Do not take Synthroid if you are allergic to it or any of its ingredients.

    Do not take Synthroid if you have an overactive thyroid gland or had a recent heart attack.

    Do not take Synthroid to treat obesity or weight loss.

  • What should I tell my healthcare provider before I take the first dose of this medication?

    Tell your healthcare provider about all prescription, over-the-counter, and herbal medications you are taking before beginning treatment with Synthroid. Also, talk to your healthcare provider about your complete medical history, especially if you have anemia, diabetes, heart disease, blood clotting disorders, or if you are pregnant, plan to become pregnant, or are breastfeeding.

  • What is the usual dosage?

    The information below is based on the dosage guidelines your healthcare provider uses. Depending on your condition and medical history, your healthcare provider may prescribe a different regimen. Do not change the dosage or stop taking your medication without your healthcare provider's approval.

    Adults and children: Your healthcare provider will prescribe the appropriate dose for you or your child based on the age, weight, and condition.

  • How should I take this medication?

    Take Synthroid exactly as prescribed by your healthcare provider. Do not change your dose or stop taking Synthroid without first talking to your healthcare provider.

    Take Synthroid on an empty stomach, 30 minutes to 1 hour before eating breakfast.

    Certain medicines, supplements, and even foods can interfere with the way your body absorbs Synthroid. Some examples are calcium or iron supplements, antacids, and certain cholesterol-lowering medicines (such as cholestyramine or colestipol). It is best to take Synthroid 4 hours before or after taking these.

    If an infant or child cannot swallow whole tablets, crush the tablet and mix it into 1-2 teaspoonfuls of water. Have the child drink the mixture right away. Do not store it for later use. Soybean infant formula can decrease the amount of Synthroid in your baby's body and should not be used to give him/her the crushed tablets.

  • What should I avoid while taking this medication?

    Do not miss any scheduled follow-up appointments with your healthcare provider.

  • What are the possible food and drug interactions associated with this medication?

    If Synthroid is taken with certain other drugs, the effects of either could be increased, decreased, or altered. Synthroid may interact with numerous medications. Therefore, it is very important that you tell your healthcare provider about any other medications you are taking.

  • May I receive this medication if I am pregnant or breastfeeding?

    You can continue taking Synthroid during pregnancy. However, a dose adjustment may be necessary. Small amounts of Synthroid are excreted in your breast milk. Tell your healthcare provider immediately if you are pregnant, plan to become pregnant, or are breastfeeding.

  • What should I do if I miss a dose of this medication?

    If you miss a dose of Synthroid, take it as soon as you remember. However, if it is almost time for your next dose, skip the one you missed and return to your regular dosing schedule. Do not take two doses at once.

  • How should I store this medication?

    Store at room temperature. Protect from light and moisture.

Meet the Pharmacists

I'm Kristen Dore, PharmD. Welcome to PDR Health!

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