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Complementary/Alternative Medicine: This monograph describes a natural or herbal product that is not subject to FDA guidelines for medicines. Patients and clinicians are advised to read package labels carefully to ensure safe and efficacious use.


Trade Name(s)

  • glycine max
  • soy protein
  • isoflavone

Ther. Class.
caloric sources

Common Uses

  • Menopausal symptoms.
  • Prevention of breast, lung, endometrial, thyroid and prostate cancers.
  • Hyperlipidemia.


Soy is the most significant dietary source of isoflavones. Pharmacologic effects of soy include lowering of homocysteine levels, inhibition of platelet aggregation, lowering of BP, inhibition of cholesterol absorption in the small bowel and lowering of LDL cholesterol. Soy isoflavones also have antioxidant, antiproliferative and estrogenic effects.

Therapeutic Effect(s):

  • Decreased cholesterol.
  • Decreased hot flashes in menopausal women.


Absorption: Unknown

Distribution: Unknown

Metabolism and Excretion: Unknown

Half-life: Unknown




Contraindicated in:

  • Hypersensitivity.
  • End stage renal disease.
  • Urinary bladder cancer (may increase risk).

Use Cautiously in:

  • Nephrolithiasis.
  • Hypothyroidism.

Adverse Reactions/Side Effects

CV: insomnia

GI: bloating, constipation, gastrointestinal upset

* CAPITALS indicate life-threatening.
Underline indicate most frequent.


Natural Drug Interaction

  • Antibiotics may ↓ effects of soy.
  • May inhibit effects of estrogensand tamoxifen.
  • May ↑ risk of hypertensive crisis with MAO inhibitors.
  • May ↓ INR of patients taking warfarin..




PO: (Adults)35–120 mg/day.




  • Monitor BP prior to and periodically during therapy.
  • Obtain a diet history, especially with regard to fat consumption.
  • Assess the frequency and intensity of hot flashes prior to and periodically during therapy.

Lab Test Considerations:

Monitor blood glucose, lipid profile, hormones, and thyroid function before and periodically during therapy.

Potential Diagnoses


  • PO: Administer as directed.

Patient/Family Teaching

  • Instruct patient to take as directed.
  • Instruct patient to notify health care professional of all Rx or OTC medications, vitamins, or herbal products being taken and to consult with health care professional before taking other medications.

Evaluation/Desired Outcomes

  • Decrease in frequency and intensity of hot flashes.
  • Reduction in serum cholesterol levels.
soy is a sample topic from the Davis's Drug Guide.

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Quiring, Courtney, et al. "Soy." Davis's Drug Guide, 16th ed., F.A. Davis Company, 2019. Washington Manual, www.unboundmedicine.com/washingtonmanual/view/Davis-Drug-Guide/109906/all/soy.
Quiring C, Sanoski CA, Vallerand AH. Soy. Davis's Drug Guide. 16th ed. F.A. Davis Company; 2019. https://www.unboundmedicine.com/washingtonmanual/view/Davis-Drug-Guide/109906/all/soy. Accessed August 21, 2019.
Quiring, C., Sanoski, C. A., & Vallerand, A. H. (2019). Soy. In Davis's Drug Guide. Available from https://www.unboundmedicine.com/washingtonmanual/view/Davis-Drug-Guide/109906/all/soy
Quiring C, Sanoski CA, Vallerand AH. Soy [Internet]. In: Davis's Drug Guide. F.A. Davis Company; 2019. [cited 2019 August 21]. Available from: https://www.unboundmedicine.com/washingtonmanual/view/Davis-Drug-Guide/109906/all/soy.
* Article titles in AMA citation format should be in sentence-case
TY - ELEC T1 - soy ID - 109906 A1 - Quiring,Courtney, AU - Sanoski,Cynthia A, AU - Vallerand,April Hazard, BT - Davis's Drug Guide UR - https://www.unboundmedicine.com/washingtonmanual/view/Davis-Drug-Guide/109906/all/soy PB - F.A. Davis Company ET - 16 DB - Washington Manual DP - Unbound Medicine ER -