SYNTHROID DOSING & MONITORING

12 precise dosing options1

With careful titration, Synthroid can help manage your patient's hypothyroidism. Synthroid should be taken as a single daily dose.

  • 25 mcg
    orange

  • 50 mcg
    white

  • 75 mcg
    violet

  • 88 mcg
    olive

  • 100 mcg
    yellow

  • 112 mcg
    rose

  • 125 mcg
    brown

  • 137 mcg
    turquoise

  • 150 mcg
    orange

  • 175 mcg
    lilac

  • 200 mcg
    pink

  • 300 mcg
    green

Tablets shown not actual size and may not represent actual color.

12 precise dosing options1

With careful titration, Synthroid can help manage your patient's hypothyroidism. Synthroid should be taken as a single daily dose.

  • 25 mcg
    orange

  • 50 mcg
    white

  • 75 mcg
    violet

  • 88 mcg
    olive

  • 100 mcg
    yellow

  • 112 mcg
    rose

  • 125 mcg
    brown

  • 137 mcg
    turquoise

  • 150 mcg
    blue

  • 175 mcg
    lilac

  • 200 mcg
    pink

  • 300 mcg
    green

Tablets shown not actual size and may not represent actual color.

25 mcg
orange

50 mcg
white

75 mcg
violet

88 mcg
olive

100 mcg
yellow

112 mcg
rose

125 mcg
brown

137 mcg
turquoise

150 mcg
blue

175 mcg
lilac

200 mcg
pink

300 mcg
green

Tablets shown not actual size and may not represent actual color.

12 precise dosing options1

With careful titration, Synthroid can help manage your patient's hypothyroidism. Synthroid should be taken as a single daily dose.

Hypothyroid medications require precise dosing and careful
monitoring

AACE & NACB TSH Range Guidelines

Thyroid disease spectrum

Abbreviations: AACE, American Association of Clinical Endocrinologists 

TSH levels alone may not be diagnostic of a thyroid disorder. Additional laboratory testing and clinical findings may be necessary.

The goal is to achieve steady TSH levels within the appropriate therapeutic range.

PRIMARY HYPOTHYROIDISM DOSING GUIDELINES ADULT* DOSING CONSIDERATIONS1

*In adolescents in whom growth and puberty are complete.

Patient Type Starting Dose Dose Adjustment and TSH Measurement
Adults diagnosed with hypothyroidism Full replacement dose is 1.6 mcg/kg/day. Some patients require a lower starting dose. Titrate dosage by 12.5 to 25 mcg increments every 4 to 6 weeks, as needed until the patient is euthyroid.
Adults at risk for atrial fibrillation or with underlying cardiac disease Lower starting dose (less than 1.6 mcg/kg/day) Titrate dosage every 6 to 8 weeks as needed until the patient is euthyroid.
Geriatric patients Lower starting dose (less than 1.6 mcg/kg/day) Titrate dosage every 6 to 8 weeks as needed until the patient is euthyroid.
Pregnant patients with new onset hypothyroidism (TSH 10 mIU per liter) 1.6 mcg/kg/day Monitor serum TSH every 4 weeks and adjust SYNTHROID dosage until serum TSH is within normal trimester-specific range.
Pregnant patients with new onset hypothyroidism (TSH <10 mIU per liter) 1.0 mcg/kg/day Monitor serum TSH every 4 weeks and adjust SYNTHROID dosage until serum TSH is within normal trimester-specific range.
  • The dosage of SYNTHROID depends on a variety of factors including: the patient's age, body weight, cardiovascular status, concomitant medical conditions (including pregnancy), concomitant medications, co-administered food and the specific nature of the condition being treated.
  • Dosing must be individualized to account for these factors and dosage adjustments made based on periodic assessment of the patient's clinical response and laboratory parameters1
  • Exercise caution with administering to patients with underlying cardiovascular disease, the elderly, and those with concomitant adrenal insufficiency1
  • For pregnant patients with pre-existing hypothyroidism, measure serum TSH and free-T4 as soon as pregnancy is confirmed and, at minimum, during each trimester of pregnancy. In pregnant patients with primary hypothyroidism, maintain serum TSH in the trimester-specific reference range.
  • If you have a patient that is taking biotin, tell them to discontinue it at least 2 days before assessing TSH and other thyroid function tests.

DISCUSS THE FOLLOWING WITH PATIENTS WHEN PRESCRIBING SYNTHROID

  • Since substitutions can be made at the pharmacy, it’s important that you discuss with patients what their Synthroid pill looks like 
  • Remind them that only Synthroid has the name “SYNTHROID” embossed on every pill and that each dose has a specific color1
  • Synthroid is taken as a single daily dose, taken on an empty stomach, preferably 30 minutes to 1 hour before breakfast

Select pill below to enlarge and see dosage

25 mcg dose; Orange Synthroid Pill

25 mcg

Orange

  • Since substitutions can be made at the pharmacy, it’s important that you discuss with patients what their Synthroid pill looks like 
  • Remind them that only Synthroid has the name “SYNTHROID” embossed on every pill and that each dose has a specific color1
  • Synthroid is taken as a single daily dose, taken on an empty stomach, preferably 30 minutes to 1 hour before breakfast

Select pill below to enlarge and see dosage

50 mcg dose; White Synthroid Pill

50 mcg

White

  • Since substitutions can be made at the pharmacy, it’s important that you discuss with patients what their Synthroid pill looks like 
  • Remind them that only Synthroid has the name “SYNTHROID” embossed on every pill and that each dose has a specific color1
  • Synthroid is taken as a single daily dose, taken on an empty stomach, preferably 30 minutes to 1 hour before breakfast

Select pill below to enlarge and see dosage

75 mcg dose; Violet Synthroid Pill

75 mcg

Violet

  • Since substitutions can be made at the pharmacy, it’s important that you discuss with patients what their Synthroid pill looks like 
  • Remind them that only Synthroid has the name “SYNTHROID” embossed on every pill and that each dose has a specific color1
  • Synthroid is taken as a single daily dose, taken on an empty stomach, preferably 30 minutes to 1 hour before breakfast

Select pill below to enlarge and see dosage

88 mcg dose; Olive Synthroid Pill

88 mcg

Olive

  • Since substitutions can be made at the pharmacy, it’s important that you discuss with patients what their Synthroid pill looks like 
  • Remind them that only Synthroid has the name “SYNTHROID” embossed on every pill and that each dose has a specific color1
  • Synthroid is taken as a single daily dose, taken on an empty stomach, preferably 30 minutes to 1 hour before breakfast

Select pill below to enlarge and see dosage

100 mcg dose; Yellow Synthroid Pill

100 mcg

Yellow

  • Since substitutions can be made at the pharmacy, it’s important that you discuss with patients what their Synthroid pill looks like 
  • Remind them that only Synthroid has the name “SYNTHROID” embossed on every pill and that each dose has a specific color1
  • Synthroid is taken as a single daily dose, taken on an empty stomach, preferably 30 minutes to 1 hour before breakfast

Select pill below to enlarge and see dosage

112 mcg dose; Rose Synthroid Pill

112 mcg

Rose

  • Since substitutions can be made at the pharmacy, it’s important that you discuss with patients what their Synthroid pill looks like 
  • Remind them that only Synthroid has the name “SYNTHROID” embossed on every pill and that each dose has a specific color1
  • Synthroid is taken as a single daily dose, taken on an empty stomach, preferably 30 minutes to 1 hour before breakfast

Select pill below to enlarge and see dosage

125 mcg dose; Brown Synthroid Pill

125 mcg

Brown

  • Since substitutions can be made at the pharmacy, it’s important that you discuss with patients what their Synthroid pill looks like 
  • Remind them that only Synthroid has the name “SYNTHROID” embossed on every pill and that each dose has a specific color1
  • Synthroid is taken as a single daily dose, taken on an empty stomach, preferably 30 minutes to 1 hour before breakfast

Select pill below to enlarge and see dosage

137 mcg dose; Turquoise Synthroid Pill

137 mcg

Turquoise

  • Since substitutions can be made at the pharmacy, it’s important that you discuss with patients what their Synthroid pill looks like 
  • Remind them that only Synthroid has the name “SYNTHROID” embossed on every pill and that each dose has a specific color1
  • Synthroid is taken as a single daily dose, taken on an empty stomach, preferably 30 minutes to 1 hour before breakfast

Select pill below to enlarge and see dosage

150 mcg dose; Blue Synthroid Pill

150 mcg

Blue

  • Since substitutions can be made at the pharmacy, it’s important that you discuss with patients what their Synthroid pill looks like 
  • Remind them that only Synthroid has the name “SYNTHROID” embossed on every pill and that each dose has a specific color1
  • Synthroid is taken as a single daily dose, taken on an empty stomach, preferably 30 minutes to 1 hour before breakfast

Select pill below to enlarge and see dosage

175 mcg dose; Lilac Synthroid Pill

175 mcg

Lilac

  • Since substitutions can be made at the pharmacy, it’s important that you discuss with patients what their Synthroid pill looks like 
  • Remind them that only Synthroid has the name “SYNTHROID” embossed on every pill and that each dose has a specific color1
  • Synthroid is taken as a single daily dose, taken on an empty stomach, preferably 30 minutes to 1 hour before breakfast

Select pill below to enlarge and see dosage

200 mcg dose; Pink Synthroid Pill

200 mcg

Pink

The FDA has determined that certain levothyroxine products are therapeutically equivalent, and can be substituted at the pharmacy with the full expectation that the substituted product will produce the same clinical effect and safety profile as the reference product.15

Tablets shown not actual size and may not represent exact color.

  • Since substitutions can be made at the pharmacy, it’s important that you discuss with patients what their Synthroid pill looks like 
  • Remind them that only Synthroid has the name “SYNTHROID” embossed on every pill and that each dose has a specific color1
  • Synthroid is taken as a single daily dose, taken on an empty stomach, preferably 30 minutes to 1 hour before breakfast

Select pill below to enlarge and see dosage

25 mcg dose; Orange Synthroid Pill

25 mcg

Orange

50 mcg dose; White Synthroid Pill

50 mcg

White

75 mcg dose; Violet Synthroid Pill

75 mcg

Violet

88 mcg dose; Olive Synthroid Pill

88 mcg

Olive

100 mcg dose; Yellow Synthroid Pill

100 mcg

Yellow

112 mcg dose; Rose Synthroid Pill

112 mcg

Rose

125 mcg dose; Brown Synthroid Pill

125 mcg

Brown

137 mcg dose; Turquoise Synthroid Pill

137 mcg

Turquoise

150 mcg dose; Blue Synthroid Pill

150 mcg

Blue

175 mcg dose; Lilac Synthroid Pill

175 mcg

Lilac

200 mcg dose; Pink Synthroid Pill

200 mcg

Pink

The FDA has determined that certain levothyroxine products are therapeutically equivalent, and can be substituted at the pharmacy with the full expectation that the substituted product will produce the same clinical effect and safety profile as the reference product.15

Tablets shown not actual size and may not represent exact color.

DOSE ADJUSTMENTS AND TSH MONITORING

Careful dose titration is necessary to avoid the consequences of
over- or undertreatment.1

  • Dosing must be individualized and adjusted based on periodic assessment of the patient’s clinical response and laboratory parameters1
  • Exercise caution with administering to patients with underlying cardiovascular disease, the elderly, and those with concomitant adrenal insufficiency1
  • Evaluate need for Synthroid dose adjustments when regularly administering Synthroid within 1 hour of food that may affect absorption (soybean flour, cottonseed meal, walnuts, dietary fiber, grapefruit juice)1
  • Peak therapeutic effect at a given dose may not be attained for 4 to 6 weeks1
  • During dose titration, TSH monitoring is generally recommended at 6- to 8-week intervals until normalization1
  • Once optimum replacement dose is attained, monitoring may be performed every 6 to 12 months and whenever there is a change in the patient’s clinical status1
  • Patients should be given the minimum dose necessary to achieve the desired response1

For secondary or tertiary hypothyroidism, TSH is not a reliable measure of Synthroid dose adequacy and should NOT be used to monitor therapy. Use free-T4 to monitor and titrate Synthroid dosing until clinically euthyroid and free-T4 is restored to upper half of normal range.1

Synthroid Patient 3

FOOD AND SUPPLEMENT
INTERACTIONS WITH SYNTHROID

Certain foods may decrease absorption and require dosing adjustments, including1:

  • Soybean flour (infant formula)
  • Cottonseed meal
  • Walnuts
  • Dietary fiber

Grapefruit juice delays the absorption of Synthroid and reduces its bioavailability.1
Iron, calcium supplements, and antacids can also decrease absorption.1

  • Synthroid should not be taken within 4 hours of these agents1

DRUG INTERACTIONS WITH SYNTHROID

Many drugs can exert effects on thyroid hormone pharmacokinetics and metabolism (eg, absorption, synthesis, secretion, catabolism, protein binding, and target tissue response) and may alter the therapeutic response to Synthroid.1

Drugs That May Decrease T4 Absorption (Hypothyroidism)
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 Effect
Phosphate Binders
(e.g., calcium carbonate, ferrous sulfate, sevelamer, lanthanum)
Phosphate binders may bind to levothyroxine. Administer SYNTHROID at least 4 hours apart from these agents.
Orlistat Monitor patients treated concomitantly with orlistat and Synthroid for changes in thyroid function.
Bile Acid Sequestrants:
(e.g., colesevelam, cholestyramine, colestipol)
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.
Ion Exchange Resins:
(e.g., Kayexalate)
 
Proton Pump Inhibitors
Sucralfate
Antacids
(e.g., aluminum & magnesium hydroxides, simethicone)

 

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.
Drugs That May Alter T4 and Triiodothyronine (T3) Serum Transport Without Affecting Free Thyroxine (FT4) Concentration (Euthyroidism)
Drug or Drug Class Effect
Clofibrate
Estrogen-containing Oral
Contraceptives
Estrogens (oral)
Heroin/Methadone
5-Fluorouracil
Mitotane
Tamoxifen
These drugs may increase serum thyroxine-binding globulin (TBG) concentration.
Androgens/Anabolic Steroids
Asparaginase
Glucocorticoids
Slow-release Nicotinic Acid
These drugs may decrease serum TBG concentration.
Potential impact (below): Administration of these agents with Synthroid results in an initial transient increase in FT4. Continued administration results in a decrease in serum T4 and normal FT4 and TSH concentrations.
Salicylates (>2 g/day) Salicylates inhibit binding of T4 and T3 to TBG and transthyretin. An initial increase in serum FT4 is followed by return of FT4 to normal levels with sustained therapeutic serum salicylate concentrations, although total T4 levels may decrease by as much as 30%.
Other Drugs:
Carbamazepine
Furosemide (>80 mg IV)
Heparin
Hydantoins
NSAIDS
- Fenamates
These drugs may cause protein-binding site displacement. Furosemide has been shown to inhibit the protein binding of T4 to TBG and albumin, causing an increase free T4 fraction in serum. Furosemide competes for T4-binding sites on TBG, prealbumin, and albumin, so that a single high dose can acutely lower the total T4 level. Phenytoin and carbamazepine reduce serum protein binding of levothyroxine, and total and free T4 may be reduced by 20% to 40%, but most patients have normal serum TSH levels and are clinically euthyroid. Closely monitor thyroid hormone parameters.
Drugs That May Alter Hepatic Metabolism of T4 (Hypothyroidism)
Potential impact: Stimulation of hepatic microsomal drug-metabolizing enzyme activity may cause increased hepatic degradation of levothyroxine, resulting in increased Synthroid requirements.
Drug or Drug Class Effect
Phenobarbital
Rifampin
Phenobarbital has been shown to reduce the response to thyroxine. Phenobarbital increases L-thyroxine metabolism by inducing uridine 5’-diphospho-glucuronosyltransferase (UGT) and leads to lower T4 serum levels. Changes in thyroid status may occur if barbiturates are added or withdrawn from patients being treated for hypothyroidism. Rifampin has been shown to accelerate the metabolism of levothyroxine.
Drugs That May Decrease Conversion of T4 to T3
Potential impact: Administration of these enzyme inhibitors decreases the peripheral conversion of T4 to T3, leading to decreased T3 levels. However, serum T4 levels are usually normal but may occasionally be slightly increased.
Drug or Drug Class Effect
Beta-adrenergic antagonists
(eg, Propranolol >160 mg/day)
In patients treated with large doses of propranolol (>160 mg/day), T3 and T4 levels change, TSH levels remain normal, and patients are clinically euthyroid. Actions of particular beta-adrenergic antagonists may be impaired when a hypothyroid patient is converted to the euthyroid state.
Glucocorticoids
(eg, Dexamethasone ≥4 mg/day)
Short-term administration of large doses of glucocorticoids may decrease serum T3 concentrations by 30% with minimal change in serum T4 levels. However, long-term glucocorticoid therapy may result in slightly decreased T3 and T4 levels due to decreased TBG production (see above).
Other Drugs: Amiodarone Amiodarone inhibits peripheral conversion of levothyroxine (T4) to triiodothyronine (T3) and may cause isolated biochemical changes (increase in serum free-T4, and decreased or normal free-T3) in clinically euthyroid patients.