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6 Interactions found for:

levothyroxine and Seroquel
Interactions Summary
  • 2 Major
  • 2 Moderate
  • 2 Minor
  • levothyroxine
  • Seroquel

Drug Interactions

No drug interactions were found for selected drugs: levothyroxine, Seroquel.

This does not necessarily mean no interactions exist. Always consult your healthcare provider.

Drug and Food Interactions

Moderate
Levothyroxine + Food

The following applies to the ingredients: Levothyroxine

The timing of meals relative to your oral levothyroxine dose can affect the absorption of the medication. Therefore, levothyroxine should be taken on a consistent schedule with regard to time of day and relation to meals to avoid large fluctuations in blood levels, which may alter its effects. In addition, absorption of levothyroxine may be decreased and/or delayed by foods such as soybean flour, cotton seed meal, walnuts, dietary fiber, calcium, calcium fortified juices and grapefruit or grapefruit juice. These foods should be avoided within several hours of dosing if possible. It is important to tell your doctor about all other medications you use, including vitamins and herbs. Do not stop using any medications without first talking to your doctor.

The following applies to the ingredients: Levothyroxine

Using multivitamin with minerals together with levothyroxine may decrease the effects of levothyroxine. You should separate the administration of levothyroxine and multivitamin with minerals by at least 4 hours. If your doctor does prescribe these medications together, you may need a dose adjustment or special test to safely use both medications. It is important to tell your doctor about all other medications you use, including vitamins and herbs. Do not stop using any medications without first talking to your doctor.

Moderate
Seroquel + Food

The following applies to the ingredients: Quetiapine (found in Seroquel)

Grapefruit or grapefruit juice should not be consumed during treatment with QUEtiapine. Grapefruit juice can significantly increase the blood levels and effects of QUEtiapine, which can increase the risk and/or severity of side effects including drowsiness; dry mouth; constipation; increased appetite; weight gain; increased blood sugar and cholesterol or triglyceride levels; cognitive and motor impairment; involuntary muscle movements involving the face, tongue, or other parts of the body; difficulty swallowing; and seizures. Consuming grapefruit juice together with QUEtiapine may also increase the risk of two potentially life-threatening, but uncommon conditions: serotonin syndrome and a change in the electrical activity of your heart called QT prolongation. Immediate medical attention is required if you experience symptoms of either condition such as: nausea, vomiting, and diarrhea; agitation; confusion; fast or irregular heartbeat; sweating; flushing; seizures; hallucinations; blood pressure changes; shaking, stiff muscles, or muscle twitching; dizziness; high body temperature; loss of coordination; lightheadedness; and/or fainting. You might be more susceptible to QT prolongation if you have heart problems, uncontrolled hypothyroidism, or electrolyte disturbances (for example, magnesium or potassium loss due to severe or prolonged diarrhea or vomiting). It is best to avoid or limit the consumption of alcohol, as it can increase drowsiness or other nervous system side effects of QUEtiapine. Extended-release formulations of QUEtiapine should be taken without food or with a light meal. Talk to your doctor if you have any questions or concerns. It is important to tell your doctor about all other medications you use, including vitamins and herbs. Do not stop using any medications without first talking to your doctor.

Drug and Pregnancy Interactions

The following applies to the ingredients: Quetiapine (found in Seroquel)

Professional Content

Safety has not been established during pregnancy.

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

Risk summary: No data are available on the use of this drug in pregnant women to inform a drug-related risk.

Comments:
-A pregnancy exposure registry is available.
-If this drug is used during pregnancy, or if the patient becomes pregnant while taking this drug, the patient should be apprised of the potential harm to the fetus.
-Neonates exposed to antipsychotic drugs during the third trimester of pregnancy are at risk for extrapyramidal and/or withdrawal symptoms following delivery.

Animal studies have revealed evidence of embryo-fetal toxicity. Limited published human data have reported no major malformations associated with use during pregnancy. There are no controlled data in human pregnancy.

Neonates exposed to antipsychotic drugs during the third trimester of pregnancy are at risk for extrapyramidal and/or withdrawal symptoms following delivery. There have been reports of agitation, hypertonia, hypotonia, tremor, somnolence, respiratory distress and feeding disorder in these neonates. These complications have varied in severity; while in some cases symptoms have been self-limited, in other cases neonates have required intensive care unit support and prolonged hospitalization.

To monitor the outcomes of pregnant women exposed to atypical antipsychotics, a National Pregnancy Registry for Atypical Antipsychotics has been established. Physicians are encouraged to register patients and pregnant women are encouraged to register themselves. For additional information: https://womensmentalhealth.org/clinical-and-research-programs/pregnancyregistry/.

AU TGA pregnancy category C: Drugs which, owing to their pharmacological effects, have caused or may be suspected of causing, harmful effects on the human fetus or neonate without causing malformations. These effects may be reversible. 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. Seroquel (quetiapine)." Astra-Zeneca Pharmaceuticals PROD (2001):
  2. Cerner Multum, Inc. "UK Summary of Product Characteristics." O 0
  3. "Product Information. Seroquel XR (quetiapine)." Astra-Zeneca Pharmaceuticals (2007):
  4. Cerner Multum, Inc. "Australian Product Information." O 0
  5. "Product Information. Seroquel (QUEtiapine)." Astra-Zeneca Pharmaceuticals (2025):
  6. "Product Information. Seroquel XR (QUEtiapine)." Astra-Zeneca Pharmaceuticals (2025):

The following applies to the ingredients: Levothyroxine

Professional Content

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 hypothyroidism during pregnancy is associated with risks to the mother and fetus

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.

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

Drug and Breastfeeding Interactions

The following applies to the ingredients: Quetiapine (found in Seroquel)

Professional Content

Use is not recommended, and a decision should be made to discontinue breastfeeding or discontinue the drug, taking into account the importance of the drug to the mother.

Excreted into human milk: Yes

Comments:
-If this drug is used, monitor infants for drowsiness and developmental milestones.
-The American Academy of Pediatrics classified other antipsychotic agents as drugs whose effect on the nursing infant is unknown but may be of concern.

Based on milk samples from a mother who received 200 mg daily throughout pregnancy and postpartum, it is estimated that an exclusively breastfed infant would receive 0.09% to 0.43% of a weight-adjusted maternal dose. Limited long-term follow-up of infants exposed to this drug during breastfeeding have shown generally normal development. However, due to the potential for serious adverse reactions in nursing infants and a lack of robust data, a decision should be made to discontinue breastfeeding or discontinue the drug, taking into account the importance of the drug to the mother.

References

  1. "Product Information. Seroquel (quetiapine)." Astra-Zeneca Pharmaceuticals PROD (2001):
  2. Cerner Multum, Inc. "UK Summary of Product Characteristics." O 0
  3. "Product Information. Seroquel XR (quetiapine)." Astra-Zeneca Pharmaceuticals (2007):
  4. Cerner Multum, Inc. "Australian Product Information." O 0
  5. United States National Library of Medicine "Toxnet. Toxicology Data Network. http://toxnet.nlm.nih.gov/cgi-bin/sis/htmlgen?LACT" (2013):
  6. Briggs GG, Freeman RK. "Drugs in Pregnancy and Lactation." Philadelphia, PA: Wolters Kluwer Health (2015):

The following applies to the ingredients: Levothyroxine

Professional Content

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: Professional 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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