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7 Interactions found for:

levothyroxine and Ozempic
Interactions Summary
  • 2 Major
  • 3 Moderate
  • 2 Minor
  • levothyroxine
  • Ozempic

Drug Interactions

Moderate
Levothyroxine + Ozempic

The following applies to the ingredients: Levothyroxine and Semaglutide (found in Ozempic)

MONITOR: The efficacy of semaglutide may be diminished by thyroid hormones. These drugs may interfere with blood glucose control. Additionally, concomitant administration of oral levothyroxine and semaglutide may result in increased levothyroxine exposure. In a controlled study with healthy volunteers, a 33% increase in total T4 exposure was observed when levothyroxine and oral semaglutide were coadministered, but levothyroxine peak plasma concentration (Cmax) was unaffected. The proposed mechanism is due to delayed gastric emptying caused by semaglutide leading to increased levothyroxine absorption. Clinical data with semaglutide and other thyroid hormones are unavailable.

ADJUST DOSING INTERVAL: This interaction applies to oral formulations of semaglutide only.

Concurrent use with other oral medicinal products may influence the absorption of oral semaglutide if they are administered at the same time. The exact mechanism of this interaction is unknown. In a pharmacokinetic trial, coadministration of oral semaglutide with five other tablets resulted in a decrease in oral semaglutide's systemic exposure (AUC) and peak plasma concentration (Cmax) of 34% and 32%, respectively. The results of this trial suggest that the presence of multiple tablets in the stomach can influence the absorption of oral semaglutide.

MANAGEMENT: Caution is advised when drugs that can interfere with glucose metabolism are prescribed to patients with diabetes. Close clinical monitoring of glycemic control is recommended following initiation or discontinuation of thyroid hormones, and the dosage of semaglutide adjusted as necessary. Increased clinical monitoring of thyroid parameters should also be considered when treating patients with both semaglutide and oral levothyroxine. Administer other oral medications, including thyroid hormones at least 30 minutes after oral semaglutide to ensure medication efficacy.

References

  1. "Product Information. Ozempic (semaglutide)." Novo Nordisk Pharmaceuticals Inc (2023):
  2. "Product Information. Rybelsus (semaglutide)." Novo Nordisk Pharmaceuticals Inc (2024):
  3. "Product Information. Wegovy (0.25 mg dose) (semaglutide)." Novo Nordisk Pharmaceuticals Inc (2024):
  4. "Product Information. Ozempic (semaglutide)." Novo Nordisk Canada Inc (2024):
  5. "Product Information. Rybelsus (semaglutide)." Novo Nordisk Canada Inc (2024):
  6. "Product Information. Wegovy (semaglutide)." Novo Nordisk Canada Inc (2024):
  7. "Product Information. Ozempic (semaglutide)." Novo Nordisk Ltd (2024):
  8. "Product Information. Rybelsus (semaglutide)." Novo Nordisk Ltd (2024):
  9. "Product Information. Wegovy FlexTouch (semaglutide)." Novo Nordisk Ltd (2024):
  10. "Product Information. Ozempic (1 mg dose) (semaglutide)." Novo Nordisk Pharmaceuticals Pty Ltd (2024):
  11. "Product Information. Wegovy Flextouch (0.25 mg dose) (semaglutide)." Novo Nordisk Pharmaceuticals Pty Ltd (2024):
  12. Hauge C, Breitschaft A, Hartoft-Nielsen ML, Jensen S, Baekdal TA "Effect of oral semaglutide on the pharmacokinetics of thyroxine after dosing of levothyroxine and the influence of co-administered tablets on the pharmacokinetics of oral semaglutide in healthy subjects: an open-label, one-sequence crossover, single-cente" Expert Opin Drug Metab Toxicol 17 (2021): 1139-48

Drug and Food Interactions

Moderate
Levothyroxine + Food

The following applies to the ingredients: Levothyroxine

ADJUST DOSING INTERVAL: Consumption of certain foods as well as the timing of meals relative to dosing may affect the oral absorption of T4 thyroid hormone (i.e., levothyroxine). T4 oral absorption is increased by fasting and decreased by foods such as soybean flour (e.g., infant formula), cotton seed meal, walnuts, dietary fiber, calcium, and calcium fortified juices. Grapefruit or grapefruit products may delay the absorption of T4 thyroid hormone and reduce its bioavailability. The mechanism of this interaction is not fully understood.

MANAGEMENT: Some manufacturers recommend administering oral T4 as a single daily dose, on an empty stomach, one-half to one hour before breakfast. In general, oral preparations containing T4 thyroid hormone should be administered on a consistent schedule with regard to time of day and relation to meals to avoid large fluctuations in serum levels. Foods that may affect T4 absorption should be avoided within several hours of dosing if possible. Consult local guidelines for the administration of T4 in patients receiving enteral feeding.

References

  1. "Product Information. Synthroid (levothyroxine)." Abbott Pharmaceutical PROD (2002):
  2. "Product Information. Armour Thyroid (thyroid desiccated)." Forest Pharmaceuticals (2022):
  3. Wohlt PD, Zheng L, Gunderson S, Balzar SA, Johnson BD, Fish JT "Recommendations for the use of medications with continuous enteral nutrition." Am J Health Syst Pharm 66 (2009): 1438-67

The following applies to the ingredients: Levothyroxine

ADJUST DOSING INTERVAL: Concurrent administration of calcium-containing products may decrease the oral bioavailability of levothyroxine by one-third in some patients. Pharmacologic effects of levothyroxine may be reduced. The exact mechanism of interaction is unknown but may involve nonspecific adsorption of levothyroxine to calcium at acidic pH levels, resulting in an insoluble complex that is poorly absorbed from the gastrointestinal tract. In one study, 20 patients with hypothyroidism who were taking a stable long-term regimen of levothyroxine demonstrated modest but significant decreases in mean free and total thyroxine (T4) levels as well as a corresponding increase in mean thyrotropin (thyroid-stimulating hormone, or TSH) level following the addition of calcium carbonate (1200 mg/day of elemental calcium) for 3 months. Four patients had serum TSH levels that were higher than the normal range. Both T4 and TSH levels returned to near-baseline 2 months after discontinuation of calcium, which further supported the likelihood of an interaction. In addition, there have been case reports suggesting decreased efficacy of levothyroxine during calcium coadministration. It is not known whether this interaction occurs with other thyroid hormone preparations.

MANAGEMENT: Some experts recommend separating the times of administration of levothyroxine and calcium-containing preparations by at least 4 hours. Monitoring of serum TSH levels is recommended. Patients with gastrointestinal or malabsorption disorders may be at a greater risk of developing clinical or subclinical hypothyroidism due to this interaction.

References

  1. Schneyer CR "Calcium carbonate and reduction of levothyroxine efficacy." JAMA 279 (1998): 750
  2. Singh N, Singh PN, Hershman JM "Effect of calcium carbonate on the absorption of levothyroxine." JAMA 283 (2000): 2822-5
  3. Csako G, McGriff NJ, Rotman-Pikielny P, Sarlis NJ, Pucino F "Exaggerated levothyroxine malabsorption due to calcium carbonate supplementation in gastrointestinal disorders." Ann Pharmacother 35 (2001): 1578-83
  4. Neafsey PJ "Levothyroxine and calcium interaction: timing is everything." Home Healthc Nurse 22 (2004): 338-9

Moderate
Ozempic + Food

The following applies to the ingredients: Semaglutide (found in Ozempic)

ADJUST DOSING INTERVAL: Taking oral semaglutide with food, beverage, or other oral medications may alter semaglutide absorption and exposure. In a controlled study with healthy volunteers, limited or no measurable semaglutide exposure was observed in subjects that were fed 30 minutes prior to taking oral semaglutide, while all subjects that fasted overnight and 30 minutes after the oral semaglutide dose had measurable semaglutide exposure. Area under the curve (AUC) and semaglutide peak plasma concentration (Cmax) were approximately 40% greater in subjects that fasted compared to those who did not. AUC and Cmax were also increased with a post-dose fasting period greater than 30 minutes.

MANAGEMENT: It is recommended that oral semaglutide be taken 30 minutes before the first food, beverage, or other oral medications of the day with no more than 4 ounces of plain water to ensure its efficacy. Fasting longer than 30 minutes after the oral semaglutide dose may lead to increased gastrointestinal side effects including nausea, vomiting, or diarrhea.

References

  1. "Product Information. Rybelsus (semaglutide)." Novo Nordisk Pharmaceuticals Inc (2024):
  2. "Product Information. Rybelsus (semaglutide)." Novo Nordisk Canada Inc (2024):
  3. "Product Information. Rybelsus (semaglutide)." Novo Nordisk Ltd (2024):
  4. Baekdal TA, Breitschaft A, Donsmark M, Maarbjerg SJ, Sondergaard FL, Borregaard J "Effect of various dosing conditions on the pharmacokinetics of oral semaglutide, a human glucagon-like peptide-1 analogue in a tablet formulation" Diabetes Ther 12 (2021): 1915-27

Drug and Pregnancy Interactions

The following applies to the ingredients: Semaglutide (found in Ozempic)

Noncirrhotic metabolic dysfunction-associated steatohepatitis (MASH): This drug should be used during pregnancy only if the benefit outweighs the risk to the fetus.
Type 2 diabetes mellitus: This drug should be used during pregnancy only if the benefit outweighs the risk to the fetus.
-According to some authorities: Use is not recommended.
Weight management: Use is not recommended.

AU TGA pregnancy category: D
US FDA pregnancy category: Not assigned

Risk summary: Limited and insufficient data are available on the use of this drug in pregnant women to inform a drug-related risk; based on animal data, this drug may cause fetal harm.

Comments:
-According to some authorities: Contraception use is recommended during therapy for patients of childbearing potential.
-This drug should be discontinued at least 2 months before a planned pregnancy due to the long half-life.
-Additionally for Wegovy:
---A pregnancy exposure registry is available.
---When a pregnancy is recognized, the patient should be apprised of the potential harm to the fetus and discontinue the drug.

Animal studies have revealed evidence of embryofetal mortality, early pregnancy losses, structural abnormalities, and growth alterations. After subcutaneous dosing in rats, rabbits, and cynomolgus monkeys during organogenesis, pharmacologically mediated maternal toxicity (reduced body weight gain and food consumption) was observed at all dose levels. In rats, reduced growth and fetal abnormalities (visceral and skeletal) were observed at the human exposure. In rabbits, early pregnancy losses and increased rates of minor fetal abnormalities (visceral and skeletal) were seen at clinically relevant exposures. In monkeys, sporadic abnormalities (vertebra, sternebra, ribs) occurred at exposures above the human exposure. Exposures at the no observed adverse effect level in all species were subclinical or only slightly higher than the plasma AUC at the maximum recommended human dose; a direct effect of this drug on the fetus cannot be excluded. Salcaprozate sodium (SNAC), an absorption enhancer in the oral tablet, has been shown to cross the placenta and reach fetal tissues in rats; SNAC was associated with increased gestation length, stillbirths, and decreased pup viability following oral dosing in pregnant rats during gestation and lactation. There are no controlled data in human pregnancy.

To monitor the outcomes of pregnant women exposed to this drug, a pregnancy registry has been established. Pregnant women exposed to Wegovy and health care providers are encouraged to contact the manufacturer at wegovypregnancyregistry.com.

Clinical considerations:
-Noncirrhotic MASH: There may be risks to the mother and fetus related to MASH with advanced liver fibrosis (e.g., increased risks of gestational diabetes, hypertensive complications, preterm birth, postpartum hemorrhage); the effect of this drug on these risks is unknown.
-Type 2 diabetes mellitus: Hypoglycemia and hyperglycemia occur more often during pregnancy in patients with pregestational diabetes; poorly controlled diabetes during pregnancy increases the maternal risk for diabetic ketoacidosis, preeclampsia, spontaneous abortions, preterm delivery, and delivery complications and increases the fetal risk for major birth defects, stillbirth, and macrosomia related morbidity.
-Weight management: Appropriate weight gain based on pre-pregnancy weight is recommended for all pregnant patients because of the obligatory weight gain that occurs in maternal tissues during pregnancy.

AU TGA pregnancy category D: Drugs which have caused, are suspected to have caused or may be expected to cause, an increased incidence of human fetal malformations or irreversible damage. These drugs may also have adverse pharmacological effects. Accompanying texts should be consulted for further details.

US FDA pregnancy category Not Assigned: The US FDA has amended the pregnancy labeling rule for prescription drug products to require labeling that includes a summary of risk, a discussion of the data supporting that summary, and relevant information to help health care providers make prescribing decisions and counsel women about the use of drugs during pregnancy. Pregnancy categories A, B, C, D, and X are being phased out.

References

  1. "Product Information. Wegovy FlexTouch (semaglutide)." Novo Nordisk Ltd (2026):
  2. "Product Information. Rybelsus (semaglutide)." Novo Nordisk Ltd 2 (2025):
  3. "Product Information. Ozempic (semaglutide)." Novo Nordisk Pharmaceuticals Inc SUPPL-37 (2025):
  4. "Product Information. Ozempic (semaglutide)." Novo Nordisk Ltd (2025):
  5. "Product Information. Ozempic (0.25 mg or 0.5 mg dose) (semaglutide)." Novo Nordisk Pharmaceuticals Pty Ltd VV-LAB-098353 v10 (2025):
  6. "Product Information. Rybelsus (semaglutide)." Novo Nordisk Pharmaceuticals Pty Ltd (2022):
  7. "Product Information. Wegovy (semaglutide)." Novo Nordisk Pharmaceuticals Inc SUPPL-33 (2026):
  8. "Product Information. Rybelsus (semaglutide)." Novo Nordisk Pharmaceuticals Inc SUPPL-30 (2026):
  9. "Product Information. Wegovy (0.25 mg dose) (semaglutide)." Novo Nordisk Pharmaceuticals Pty Ltd AU-Wegovy-PI-mPFS VV (2026):

The following applies to the ingredients: Levothyroxine

Use is considered acceptable.

AU TGA pregnancy category: A
US FDA pregnancy category: Not Assigned

Risk summary: No increased rates of major birth defects or miscarriages have been reported with use during pregnancy; untreated maternal hypothyroidism during pregnancy is associated with a higher rate of complications, including spontaneous abortion, gestational hypertension, pre-eclampsia, stillbirth, and premature delivery, as well as potential adverse effects on fetal neurocognitive development.

Comments:
-Thyroid replacement therapy should not be discontinued during pregnancy; hypothyroidism diagnosed during pregnancy should be promptly treated.
-Monitor TSH levels and adjust doses as needed.
-According to some authorities, combination therapy with antithyroid agents for hyperthyroidism is not recommended during pregnancy due to the risk of fetal hypothyroidism from higher doses of antithyroid agents crossing the placenta.

Animal studies have not been conducted. There is a long history of using this drug in pregnant women and this experience has not shown increased rates of fetal malformations, miscarriages or other adverse maternal or fetal outcomes. Hypothyroidism during pregnancy is associated with a higher rate of complications, including spontaneous abortion, pre-eclampsia, stillbirth and premature delivery. Maternal hypothyroidism may have an adverse effect on fetal neurocognitive development. Pregnant women taking this drug should have their TSH measured during each trimester and dose adjusted as appropriate. Patients will generally return to their pre-pregnancy dose after delivery. There are no controlled data in human pregnancy.

AU TGA pregnancy category A: Drugs which have been taken by a large number of pregnant women and women of childbearing age without any proven increase in the frequency of malformations or other direct or indirect harmful effects on the fetus having been observed.

US FDA pregnancy category Not Assigned: The US FDA has amended the pregnancy labeling rule for prescription drug products to require labeling that includes a summary of risk, a discussion of the data supporting that summary, and relevant information to help health care providers make prescribing decisions and counsel women about the use of drugs during pregnancy. Pregnancy categories A, B, C, D, and X are being phased out.

References

  1. "Product Information. Synthroid (levothyroxine)." Abbott Pharmaceutical PROD (2002):
  2. Cerner Multum, Inc. "UK Summary of Product Characteristics." O 0
  3. Pharmaceutical Society of Australia "APPGuide online. Australian prescription products guide online. http://www.appco.com.au/appguide/default.asp" (2006):
  4. Cerner Multum, Inc. "Australian Product Information." O 0
  5. "Product Information. Levothyroxine Sodium (levothyroxine)." Fresenius Kabi USA, LLC (2021):
  6. "Product Information. Synthroid (levothyroxine)." AbbVie US LLC (2024):
  7. "Product Information. Tirosint (levothyroxine)." IBSA Pharma Inc. (2022):
  8. "Product Information. Thyquidity (levothyroxine)." Azurity Pharmaceuticals (2020):
  9. "Product Information. Levothyroxine Sodium (levothyroxine)." Glenmark Pharmaceuticals Europe Ltd (2025):
  10. "Product Information. Levothyroxine Sodium (levothyroxine)." SERB (2025):

Drug and Breastfeeding Interactions

The following applies to the ingredients: Semaglutide (found in Ozempic)

Only injectable forms of this drug should be used during breastfeeding.
-According to some authorities: Use is not recommended.
-According to some authorities: Breastfeeding is not recommended during use of the oral form of this drug.

Excreted into human milk: Unknown
Excreted into animal milk: Yes

Comments:
-Injectable formulations: Developmental and health benefits of breastfeeding should be considered as well as the mother's clinical need for this drug. The effects in the nursing infant are unknown; potential adverse effects in the breastfed child due to this drug or the mother's underlying condition should be considered.
---According to some authorities: A risk to a breastfed child cannot be excluded.
-Oral formulations: The absorption enhancer (salcaprozate sodium [SNAC]) and/or its metabolites are present in human milk; enzyme activity involved in SNAC clearance may be lower in infants compared to adults, leading to higher SNAC plasma levels in neonates and infants.
---There is the potential for serious adverse reactions in breastfed infants due to possible SNAC accumulation.

This drug was not detectable in the milk of mothers receiving the subcutaneous formulation. Data from a lactation study with the oral tablet formulation reported drug levels below the lower limit of quantification in human milk.

In a study involving nursing mothers using subcutaneous doses of this drug, milk samples showed no measurable drug levels. If present at the detection limit, the relative infant dose was estimated to be very low. Additionally, breastfed infants of these mothers showed normal growth and development during the period of exposure through breast milk. This drug has poor oral absorption, with a maximum bioavailability of approximately 1% in adults.

Milk samples were collected (at 0, 12, and 24 hours after dosing) from 8 nursing mothers using this drug subcutaneously (0.25 to 1 mg/week); their infants (4 to 23 months old) were mixed fed, receiving breast milk for 3 to 9 weeks during maternal dosing. None of the milk samples contained any measurable drug (less than 1.7 mcg/L), and the mothers reported normal growth and development for their infants. According to author calculation, if drug milk levels were at the detection limit, the relative infant dose would have averaged 1.12%; this did not account for the poor oral absorption of the drug and maximum bioavailability of 1% in adults.

References

  1. Bethesda (MD): National Institute of Child Health and Human Development (US) "Semaglutide - Drugs and Lactation Database (LactMed) https://www.ncbi.nlm.nih.gov/books/NBK500980/" (2026):
  2. "Product Information. Wegovy FlexTouch (semaglutide)." Novo Nordisk Ltd (2026):
  3. "Product Information. Rybelsus (semaglutide)." Novo Nordisk Ltd 2 (2025):
  4. "Product Information. Ozempic (semaglutide)." Novo Nordisk Pharmaceuticals Inc SUPPL-37 (2025):
  5. "Product Information. Ozempic (semaglutide)." Novo Nordisk Ltd (2025):
  6. "Product Information. Ozempic (0.25 mg or 0.5 mg dose) (semaglutide)." Novo Nordisk Pharmaceuticals Pty Ltd VV-LAB-098353 v10 (2025):
  7. "Product Information. Rybelsus (semaglutide)." Novo Nordisk Pharmaceuticals Pty Ltd (2022):
  8. "Product Information. Wegovy (semaglutide)." Novo Nordisk Pharmaceuticals Inc SUPPL-33 (2026):
  9. "Product Information. Rybelsus (semaglutide)." Novo Nordisk Pharmaceuticals Inc SUPPL-30 (2026):
  10. "Product Information. Wegovy (0.25 mg dose) (semaglutide)." Novo Nordisk Pharmaceuticals Pty Ltd AU-Wegovy-PI-mPFS VV (2026):

The following applies to the ingredients: Levothyroxine

Use is considered acceptable

Excreted into human milk: Yes

Comments:
-Levothyroxine (T4) is a normal component of human milk; limited data on exogenous replacement doses during breastfeeding have not shown an adverse effect in nursing infants.
-Levothyroxine dose requirements may be increased in the postpartum period compared to prepregnancy requirements in patients with Hashimoto's thyroiditis.
-The presence of thyroid hormone in breast milk does not appear to interfere with neonatal thyroid screening.

References

  1. "Product Information. Synthroid (levothyroxine)." Abbott Pharmaceutical PROD (2002):
  2. Jansson L, Ivarsson S, Larsson I, Ekman R "Tri-iodothyronine and thyroxine in human milk." Acta Paediatr Scand 72 (1983): 703-5
  3. Moller B, Bjorkhem I, Falk O, Lantto O, Lafsson A "Identification of thyroxine in human breast milk by gas chromatography-mass spectrometry." J Clin Endocrinol Metab 56 (1983): 30-4
  4. Mizuta H, Amino N, Ichihara K, et al. "Thyroid hormones in human milk and their influence on thyroid function of breast-fed babies." Pediatr Res 17 (1983): 468-71
  5. Hahn HB, Spiekerman AM, Otto R, Hossalla DE "Thyroid function tests in neonates fed human milk." Am J Dis Child 137 (1983): 220-2
  6. Cerner Multum, Inc. "UK Summary of Product Characteristics." O 0
  7. Pharmaceutical Society of Australia "APPGuide online. Australian prescription products guide online. http://www.appco.com.au/appguide/default.asp" (2006):
  8. Cerner Multum, Inc. "Australian Product Information." O 0
  9. United States National Library of Medicine "Toxnet. Toxicology Data Network. http://toxnet.nlm.nih.gov/cgi-bin/sis/htmlgen?LACT" (2013):

Therapeutic Duplication Warnings

No warnings were found for your selected drugs.

Therapeutic duplication warnings are only returned when drugs within the same group exceed the recommended therapeutic duplication maximum.

Switch to: Consumer Interactions

Drug Interaction Classification

These classifications are only a guideline. The relevance of a particular drug interaction to a specific individual is difficult to determine. Always consult your healthcare provider before starting or stopping any medication.

Major Highly clinically significant. Avoid combinations; the risk of the interaction outweighs the benefit.
Moderate Moderately clinically significant. Usually avoid combinations; use it only under special circumstances.
Minor Minimally clinically significant. Minimize risk; assess risk and consider an alternative drug, take steps to circumvent the interaction risk and/or institute a monitoring plan.
Unknown No interaction information available.

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