What home remedies and supplements can interact with prescribed medications?

Common Home Remedies and Supplements That Can Affect Treatment

Patients should discontinue St. John's wort, grapefruit products, and several herbal supplements at least 2 weeks before surgery or when starting medications metabolized by cytochrome P450 enzymes, as these create clinically significant drug interactions that can reduce medication efficacy or increase toxicity. 1

Critical Supplements Requiring Discontinuation

St. John's Wort - Highest Risk

• Must be held for 2 weeks before surgery due to multiple constituents with long half-lives (such as hypericin) and its induction of cytochrome P450 3A4 (CYP3A4), which reduces plasma concentrations of drugs metabolized by this enzyme. 1
• Reduces irinotecan's active metabolite (SN-38) by 42% in cancer patients, potentially compromising chemotherapy efficacy. 1
• Interacts with antidepressants, immunosuppressants, anticoagulants, and numerous other medications by accelerating their metabolism. 2, 3
• Accounts for a substantial portion of clinically significant herb-drug interactions in clinical practice. 3

Grapefruit and Citrus Products

• Grapefruit juice inhibits cytochrome P450 3A4 in the gut and liver, increasing blood levels of ciclosporin and most statins unpredictably. 1
• The effect is variable between individuals and long-lasting; patients on affected medications should avoid grapefruit completely, not just separate timing of ingestion. 1
• Active constituents include furanocoumarins and flavonoids that create sustained enzyme inhibition. 1

Supplements Affecting Bleeding Risk

Hold 2 Weeks Before Surgery

• Garlic, ginkgo, ginger, turmeric, vitamin E, saw palmetto, horse chestnut, and resveratrol should be discontinued 2 weeks preoperatively due to antiplatelet effects and bleeding risk. 1
• Ginkgo displaces platelet-activating factor from binding sites, decreasing coagulation and interacting with warfarin. 1
• Garlic, valerian, kava, ginkgo, and St. John's wort account for 68% of potential clinically significant interactions in clinical practice. 3

Safe to Continue

• Fish oil/omega-3 fatty acids can be continued despite prior bleeding concerns, as prospective studies have not confirmed increased bleeding risk. 1
• Green tea extract may be continued; while it may increase bleeding risk theoretically, the catechins improve diastolic cardiac function. 1

Supplements Affecting Blood Glucose

High-Risk Hypoglycemia Interactions

• Black seed oil, alpha-lipoic acid, American ginseng, chromium, fenugreek, and Panax ginseng should ideally be held 2 weeks before surgery due to effects on glucose metabolism. 1
• Black seed oil improves insulin resistance and increases insulin sensitivity, creating hypoglycemia risk when combined with metformin, sulfonylureas, or insulin; increase glucose monitoring frequency and prepare to reduce diabetes medication doses. 4
• These supplements upregulate glucose transporters and insulin receptors, potentiating antidiabetic medications. 1

Supplements Affecting Blood Pressure

Antihypertensive Interactions

• Black seed oil contains andrographolide and other diterpenes that lower blood pressure, potentially causing additive hypotensive effects with ACE inhibitors like lisinopril. 4
• Monitor blood pressure more frequently when black seed oil is initiated or discontinued in patients on antihypertensives. 4
• Casein peptides cause angiotensin-converting enzyme inhibition and may increase hypotension risk. 1

Supplements Causing CNS Depression

Hold 2 Weeks Preoperatively

• Kava, lemon balm, and skullcap should be held 2 weeks before surgery due to lack of pharmacokinetic information and potential to exacerbate CNS depression perioperatively. 1
• Valerian can be continued as it appears safe and may protect against cognitive dysfunction perioperatively. 1
• Consider continuing lavender extract and hops as there is no convincing evidence of significant interactions with CNS depressants. 1

Supplements Affecting Serotonin Levels

• 5-hydroxytryptophan, L-tryptophan, and S-adenosylmethionine should be held 24 hours before surgery due to rapid metabolism and short elimination half-lives. 1
• If continued to surgery day, use caution with serotonergic medications (meperidine, tramadol) to avoid serotonin syndrome. 1

High-Risk Supplements to Avoid Completely

• Garcinia cambogia and kratom are not recommended due to potential for serious adverse effects; discontinue if possible. 1
• Garcinia cambogia contains hydroxycitric acid associated with hepatotoxicity. 1
• Kratom has opioid agonist properties and should be tapered due to withdrawal potential; the FDA has warned against its use. 1

Medication Classes Most Affected by Supplement Interactions

Highest Risk Medication Categories

• Antithrombotic medications, sedatives, antidepressants, and antidiabetic agents account for 94% of potential clinically significant interactions with supplements. 3
• Warfarin, insulin, aspirin, digoxin, and ticlopidine have the greatest number of reported interactions with herbal supplements. 5
• Medications affecting the central nervous system or cardiovascular system have more documented interactions with supplements. 5

Specific High-Risk Combinations

• ACE inhibitors interact with potassium-containing supplements, "low-salt" substitutes with high potassium content, and NSAIDs. 1
• Statins combined with ciclosporin produce marked increases in statin levels with increased rhabdomyolysis risk. 1
• Digoxin clearance is reduced by ciclosporin, causing digoxin toxicity. 1

Critical Communication and Documentation Strategies

Overcoming Disclosure Barriers

• 31% to 68% of cancer patients and survivors who use supplements do not discuss their use with physicians; health care providers often fail to ask or record supplement use in medical charts. 1
• Document all herbal supplement use at every clinical encounter, as commercially available products lack standardization and vary widely in active ingredient content. 4
• Use open-ended questions about "vitamins, herbs, teas, or natural products" rather than just asking about "medications" to improve disclosure rates. 4

Patient Education Points

• Patients should be advised to avoid NSAIDs purchased over-the-counter and salt substitutes high in potassium when taking ACE inhibitors. 1
• Develop a trusting relationship that encourages patients to discuss dietary supplement use, as most patients do not voluntarily disclose this information. 2
• Patients often believe dietary supplements are beneficial (only 3.7% perceive them as "not beneficial at all"), requiring education about interaction risks. 1

Common Pitfalls to Avoid

• Never assume patients will volunteer supplement information; specifically ask at every visit using inclusive terminology. 1, 2
• Do not rely solely on in vitro studies predicting interactions; many have not been confirmed or have been refuted in human clinical trials. 2
• Recognize that antioxidant supplement use during radiation therapy may alter treatment efficacy; α-tocopherol supplementation during head and neck cancer radiation was associated with higher recurrence rates. 1
• Be aware that folic acid may foster progression of pre-malignant colonic lesions after carcinogenic processes have been initiated. 1