Clinical Colon Cleansing Ingredients & Drug Interactions

Theoretically, due to potential diuretic effects, marshmallow might reduce excretion and increase levels of lithium.
Marshmallow is thought to have diuretic properties. To avoid lithium toxicity, the dose of lithium might need to be decreased when used with marshmallow.

Theoretically, marshmallow flower might have antiplatelet effects.
Animal research suggests that marshmallow flower extract has antiplatelet effects. However, the root and leaf of marshmallow, not the flower, are the plant parts most commonly found in dietary supplements. Theoretically, use of marshmallow flower with anticoagulant/antiplatelet drugs can have additive effects, and might increase the risk for bleeding in some patients.

Theoretically, mucilage in marshmallow might impair absorption of oral drugs.
Marshmallow contains mucilage which can affect oral drug absorption. To avoid changes in absorption, take marshmallow 30-60 minutes after oral medications.

Theoretically, slippery elm may slow the absorption and reduce serum levels of oral drugs.
Slippery elm inner bark contains mucilage, which may interfere with the absorption of orally administered drugs.

Theoretically, taking ashwagandha with antidiabetes drugs might increase the risk of hypoglycemia.
There is preliminary clinical evidence suggesting that ashwagandha might lower blood glucose levels. Theoretically, ashwagandha might have additive effects when used with antidiabetes drugs and increase the risk of hypoglycemia.

Theoretically, taking ashwagandha with antihypertensive drugs might increase the risk of hypotension.
Animal research suggests that ashwagandha might lower systolic and diastolic blood pressure. Theoretically, ashwagandha might have additive effects when used with antihypertensive drugs and increase the risk of hypotension.

Theoretically, taking ashwagandha might increase the sedative effects of benzodiazepines.
There is preliminary evidence that ashwagandha might have an additive effect with diazepam (Valium) and clonazepam (Klonopin). This may also occur with other benzodiazepines.

Theoretically, taking ashwagandha might increase the sedative effects of CNS depressants.
Ashwagandha seems to have sedative effects. Theoretically, this may potentiate the effects of barbiturates, other sedatives, and anxiolytics.

Theoretically, taking ashwagandha with hepatotoxic drugs might increase the risk of liver damage.
Ashwagandha has been linked to cases of acute hepatitis, liver failure, hepatic encephalopathy, autoimmune hepatitis, the need for liver transplantation, and death due to liver failure.

Theoretically, taking ashwagandha might decrease the effects of immunosuppressants.
Ashwagandha has demonstrated immunostimulant effects in humans. Animal research has shown that ashwagandha can attenuate the immunosuppression caused by cyclophosphamide.

Ashwagandha might increase the effects and adverse effects of thyroid hormone.
Concomitant use of ashwagandha with thyroid hormones may cause additive therapeutic and adverse effects. Preliminary clinical research and animal studies suggest that ashwagandha boosts thyroid hormone synthesis and secretion. In one clinical study, ashwagandha increased triiodothyronine (T3) and thyroxine (T4) levels by 41.5% and 19.6%, respectively, and reduced serum TSH levels by 17.4% from baseline in adults with subclinical hypothyroidism.

Theoretically, ashwagandha might decrease the levels and clinical effects of CYP1A2 substrates.
In vitro research shows that ashwagandha extract induces CYP1A2 enzymes.

Theoretically, ashwagandha might decrease the levels and clinical effects of CYP3A4 substrates.
In vitro research shows that ashwagandha extract induces CYP3A4 enzymes.

Some animal studies have reported that ashwagandha can enhance serotonergic transmission by altering certain serotonin (5-HT) receptors. However, there is no evidence to suggest that ashwagandha increases the risk of serotonin-related effects, and there have been no published case reports of serotonin syndrome when combined with other serotonergic drugs. Nevertheless, due to the lack of extensive studies on the matter and the fact that ashwagandha appears to affect serotonergic pathways, it would be prudent to exercise caution when combining it with drugs that affect serotonin. [References: - Effects of Withania somnifera (Ashwaga ndha) on Stress and the Stress-Related Neuropsychiatric Disorders Anxiety, Depression, and Insomnia. Curr Neuropharmacol. 2021 Sep 14; 19: 1468–1495. - A Prospective, Randomized Double-Blind, Placebo-Controlled Study of Safety and Efficacy of a High-Concentration Full-Spectrum Extract of Ashwagandha Root in Reducing Stress and Anxiety in Adults. https://www.ncbi.nlm.nih.gov/pmc/articles/PMC3573577/]

Turmeric has antioxidant effects. Theoretically, this may reduce the activity of chemotherapy drugs that generate free radicals. However, research is conflicting.
In vitro research suggests that curcumin, a constituent of turmeric, inhibits mechlorethamine-induced apoptosis of breast cancer cells by up to 70%. Also, animal research shows that curcumin inhibits cyclophosphamide-induced tumor regression. However, some in vitro research shows that curcumin does not affect the apoptosis capacity of etoposide. Also, other laboratory research suggests that curcumin might augment the cytotoxic effects of alkylating agents. Reasons for the discrepancies may relate to the dose of curcumin and the specific chemotherapeutic agent. Lower doses of curcumin might have antioxidant effects while higher doses might have pro-oxidant effects. More evidence is needed to determine what effect, if any, turmeric might have on alkylating agents.

Taking turmeric with amlodipine may increase levels of amlodipine.
Animal research shows that giving amlodipine 1 mg/kg as a single dose following the use of turmeric extract 200 mg/kg daily for 2 weeks increases the maximum concentration and area under the curve by 53% and 56%, respectively, when compared with amlodipine alone. Additional animal research shows that taking amlodipine 1 mg/kg with a curcumin 2 mg/kg pretreatment for 10 days increases the maximum concentration and area under the curve by about 2-fold when compared with amlodipine alone.

Turmeric may have antiplatelet effects and may increase the risk of bleeding if used with anticoagulant or antiplatelet drugs. However, research is conflicting.
Curcumin, a constituent of turmeric, has demonstrated antiplatelet effects in vitro. Furthermore, two case reports have found that taking turmeric along with warfarin or fluindione was associated with an increased international normalized ratio (INR). However, one clinical study in healthy volunteers shows that taking curcumin 500 mg daily for 3 weeks, alone or with aspirin 100 mg, does not increase antiplatelet effects or bleeding risk. It is possible that the dose of turmeric used in this study was too low to produce a notable effect.

Theoretically, taking turmeric with antidiabetes drugs might increase the risk of hypoglycemia.
Animal research and case reports suggest that curcumin, a turmeric constituent, can reduce blood glucose levels in patients with diabetes. Furthermore, clinical research in adults with type 2 diabetes shows that taking curcumin 475 mg daily for 10 days prior to taking glyburide 5 mg decreased postprandial glucose levels for up to 24 hours when compared with glyburide alone, despite the lack of a significant pharmacokinetic interaction. Other clinical studies in patients with diabetes show that taking curcumin daily can reduce blood glucose levels when compared with placebo.

Turmeric has antioxidant effects. Theoretically, this may reduce the activity of chemotherapy drugs that generate free radicals. However, research is conflicting.
In vitro and animal research shows that curcumin, a constituent of turmeric, inhibits doxorubicin-induced apoptosis of breast cancer cells by up to 65%. However, curcumin does not seem to affect the apoptosis capacity of daunorubicin. In fact, some research shows that curcumin might augment the cytotoxic effects of antitumor antibiotics, increasing their effectiveness. Reasons for the discrepancies may relate to the dose of curcumin and the chemotherapeutic agent. Lower doses of curcumin might have antioxidant effects while higher doses might have pro-oxidant effects. More evidence is needed to determine what effects, if any, antioxidants such as turmeric have on antitumor antibiotics.

Turmeric might increase or decrease levels of drugs metabolized by CYP3A4.
In vitro and animal research show that turmeric and its constituents curcumin and curcuminoids inhibit CYP3A4. Also, 8 case reports from the World Health Organization (WHO) adverse drug reaction database describe increased toxicity in patients taking turmeric and cancer medications that are CYP3A4 substrates, including everolimus, ruxolitinib, ibrutinib, and palbociclib, and bortezomib. In another case report, a transplant patient presented with acute nephrotoxicity and elevated tacrolimus levels after consuming turmeric powder at a dose of 15 or more spoonfuls daily for ten days prior. It was thought that turmeric increased levels of tacrolimus due to CYP3A4 inhibition.
Conversely, other in vitro research suggests that turmeric induces CYP3A4 activity, leading to reduced levels of CYP3A4 substrates. An animal model suggests that induction of CYP3A4 occurs after daily curcumin use for 1 week. However, the induction of CYP3A4 by turmeric has not been reported in humans.

Theoretically, turmeric might increase the risk of liver damage when taken with hepatotoxic drugs.
There is concern that turmeric might cause hepatotoxicity, especially when highly bioavailable formulations are used in high doses.

Theoretically, turmeric might have additive effects when used with hepatotoxic drugs such as methotrexate.
In one case report, a 39-year-old female taking methotrexate, turmeric, and linseed oil developed hepatotoxicity.

Theoretically, turmeric might increase blood levels of OATP4C1 substrates.
In vitro research shows that the turmeric constituent curcumin competitively inhibits OATP4C1 transport. This transporter is expressed in the kidney and facilitates the renal excretion of certain drugs. Theoretically, taking turmeric might decrease renal excretion of OATP substrates.

Turmeric might increase the effects and adverse effects of sulfasalazine.
Clinical research shows that taking the turmeric constituent, curcumin, can increase blood levels of sulfasalazine by 3.2-fold.

Turmeric might increase the effects and adverse effects of tacrolimus.
In one case report, a transplant patient presented with acute nephrotoxicity and elevated tacrolimus levels of 29 ng/mL. The patient previously had tacrolimus levels within the therapeutic range at 9.7 ng/mL. Ten days prior to presenting at the emergency room the patient started consumption of turmeric powder at a dose of 15 or more spoonfuls daily. It was thought that turmeric increased levels of tacrolimus due to cytochrome P450 3A4 (CYP3A4) inhibition. In vitro and animal research show that turmeric and its constituent curcumin inhibit CYP3A4.

Turmeric may reduce the absorption of talinolol in some situations.
Clinical research shows that taking curcumin for 6 days decreases the bioavailability of talinolol when taken together on the seventh day. The clinical significance of this effect is unclear.

Theoretically, turmeric might reduce the levels and clinical effects of tamoxifen.
In a small clinical trial in patients with breast cancer taking tamoxifen 20-30 mg daily, adding curcumin 1200 mg plus piperine 10 mg three times daily reduces the 24-hour area under the curve of tamoxifen and the active metabolite endoxifen by 12.8% and 12.4%, respectively, as well as the maximum concentrations of tamoxifen, when compared with tamoxifen alone. However, in the absence of piperine, the area under the curve for endoxifen and the maximum concentration of tamoxifen were not significantly reduced. Effects were most pronounced in patients who were extensive cytochrome P450 (CYP) 2D6 metabolizers.

Turmeric has antioxidant effects. There is some concern that this may reduce the activity of chemotherapy drugs that generate free radicals. However, research is conflicting.
In vitro research shows that curcumin, a constituent of turmeric, inhibits camptothecin-induced apoptosis of breast cancer cells by up to 71%. However, other in vitro research shows that curcumin augments the cytotoxic effects of camptothecin. Reasons for the discrepancies may relate to the dose of curcumin and the chemotherapeutic agents. Lower doses of curcumin might have antioxidant effects while higher doses might have pro-oxidant effects. More evidence is needed to determine what effect, if any, turmeric might have.

Theoretically, turmeric might increase or decrease levels of tramadol.
Animal research suggests that a single dose of curcumin, a constituent of turmeric, may increase tramadol's maximum concentration (Cmax) by inhibiting metabolism, while continued daily use for 7 days may reduce the area under the curve (AUC) due to the induction of drug-metabolizing enzymes such as cytochrome P450 3A4 (CYP3A4). However, this interaction has not been reported in humans.

Turmeric might increase the risk of bleeding with warfarin.
One case of increased international normalized ratio (INR) has been reported for a patient taking warfarin who began taking turmeric. Prior to taking turmeric, the patient had stable INR measurements. Within a few weeks of starting turmeric supplementation, the patient's INR increased to 10. Additionally, curcumin, the active constituent in turmeric, has demonstrated antiplatelet effects in vitro, which may produce additive effects when taken with warfarin.

Theoretically, turmeric might increase levels of drugs metabolized by CYP1A2. However, research is conflicting.
In vitro and animal research show that the turmeric constituent, curcumin, inhibits CYP1A2. However, other in vitro research suggests that curcumin does not significantly affect CYP1A2.

Theoretically, turmeric might increase blood levels of oral docetaxel.
Animal research suggests that the turmeric constituent, curcumin, enhances the oral bioavailability of docetaxel. However, the significance of this interaction is unclear, as this drug is typically administered intravenously in clinical settings.

Theoretically, large amounts of turmeric might interfere with hormone replacement therapy through competition for estrogen receptors.
In vitro research shows that curcumin, a constituent of turmeric, displaces the binding of estrogen to its receptors.

Theoretically, taking turmeric and glyburide in combination might increase the risk of hypoglycemia.
Clinical research shows that taking curcumin 475 mg daily for 10 days prior to taking glyburide 5 mg increases blood levels of glyburide by 12% at 2 hours after the dose in patients with type 2 diabetes. While maximal blood concentrations of glyburide were not affected, turmeric modestly decreased postprandial glucose levels for up to 24 hours when compared to glyburide alone, possibly due to the hypoglycemic effect of turmeric demonstrated in animal research.

Theoretically, turmeric might increase the effects of losartan.
Research in hypertensive rats shows that taking turmeric can increase the hypotensive effects of losartan.

Theoretically, turmeric might increase the effects and adverse effects of norfloxacin.
Animal research shows that taking curcumin, a turmeric constituent, can increase blood levels of orally administered norfloxacin.

Theoretically, turmeric might increase the absorption of P-glycoprotein substrates.
In vitro and animal research shows that curcuminoids and other constituents found in turmeric can inhibit P-glycoprotein expression and activity.

Theoretically, turmeric might alter blood levels of paclitaxel, although any effect may not be clinically relevant.
Clinical research in adults with breast cancer receiving intravenous paclitaxel suggests that taking turmeric may modestly alter paclitaxel pharmacokinetics. Patients received paclitaxel on day 1, followed by either no treatment or turmeric 2 grams daily from days 2-22. Pharmacokinetic modeling suggests that turmeric reduces the maximum concentration and area under the curve of paclitaxel by 12.1% and 7.7%, respectively. However, these changes are not likely to be considered clinically relevant. Conversely, animal research suggests that curcumin, a constituent of turmeric, enhances the oral bioavailability of paclitaxel. However, the significance of this interaction is unclear, as this drug is typically administered intravenously in clinical settings.

Ginger may have antiplatelet effects and may increase the risk of bleeding if used with anticoagulant or antiplatelet drugs. However, research is conflicting.
Laboratory research suggests that ginger inhibits thromboxane synthetase and decreases platelet aggregation. However, this has not been demonstrated unequivocally in humans, with mixed results from clinical trials. Theoretically, excessive amounts of ginger might increase the risk of bleeding when used with anticoagulant/antiplatelet drugs.

Theoretically, taking ginger with antidiabetes drugs might increase the risk of hypoglycemia.
Animal and human research suggests that ginger might increase insulin levels and/or decrease blood glucose levels.

Ginger might increase or decrease the levels of CYP3A4 substrates.
In vitro research and some case reports suggest that ginger inhibits CYP3A4 activity. Three case reports from the World Health Organization (WHO) adverse drug reaction database describe increased toxicity in patients taking ginger and cancer medications that are CYP3A4 substrates (imatinib, dabrafenib, and crizotinib). However, the causality of this interaction is unclear due to the presence of multiple interacting drugs and routes of administration.
Conversely, other in vitro research suggests that ginger induces CYP3A4 activity, leading to reduced levels of CYP3A4 substrates. However, this interaction has not been reported in humans.

Theoretically, ginger might increase levels of losartan and the risk of hypotension.
In animal research, ginger increased the levels and hypotensive effects of a single dose of losartan. It is not clear if ginger alters the concentration or effects of losartan when taken continuously. Additionally, this interaction has not been shown in humans.

Ginger may have antiplatelet effects and increase the risk of bleeding if used with nifedipine.
Clinical research shows that combined treatment with ginger 1 gram plus nifedipine 10 mg significantly inhibits platelet aggregation when compared to nifedipine or ginger alone.

Ginger might increase the absorption and blood levels of P-glycoprotein (P-gp) substrates.
In vitro research and case reports suggest that ginger inhibits drug efflux by P-gp, potentially increasing absorption and serum levels of P-gp substrates. Two case reports from the World Health Organization (WHO) adverse drug reaction database describe increased toxicity in patients taking ginger and cancer medications that are P-gp substrates (trametinib, crizotinib). However, the causality of this interaction is unclear due to the presence of multiple interacting drugs and routes of administration.

Ginger might increase the risk of bleeding with phenprocoumon.
Phenprocoumon, a warfarin-related anticoagulant, might increase the international normalized ratio (INR) when taken with ginger. There is one case report of a 76-year-old woman with a stable INR on phenprocoumon that increased to greater than 10 when she began consuming dried ginger and ginger tea.

Ginger might increase the risk of bleeding with warfarin.
Laboratory research suggests that ginger might inhibit thromboxane synthetase and decrease platelet aggregation. In one case report, ginger increased the INR when taken with phenprocoumon, which has similar pharmacological effects as warfarin. In another case report, ginger increased the INR when taken with a combination of warfarin, hydrochlorothiazide, and acetaminophen. A longitudinal analysis suggests that taking ginger increases the risk of bleeding in patients taking warfarin for at least 4 months. However, research in healthy people suggests that ginger has no effect on INR, or the pharmacokinetics or pharmacodynamics of warfarin. Until more is known, monitor INRs closely in patients taking large amounts of ginger.

Theoretically, taking ginger with calcium channel blockers might increase the risk of hypotension.
Some animal and in vitro research suggests that ginger has hypotensive and calcium channel-blocking effects. Another animal study shows that concomitant administration of ginger and the calcium channel blocker amlodipine leads to greater reductions in blood pressure when compared with amlodipine alone.

Theoretically, when taken prior to cyclosporine, ginger might decrease cyclosporine levels.
In an animal model, ginger juice taken 2 hours prior to cyclosporine administration reduced the maximum concentration and area under the curve of cyclosporine by 51% and 40%, respectively. This effect was not observed when ginger juice and cyclosporine were administered at the same time.

Theoretically, ginger might increase the levels of CYP1A2 substrates.
In vitro research shows that ginger inhibits CYP1A2 activity. However, this interaction has not been reported in humans.

Theoretically, ginger might increase the levels of CYP2B6 substrates.
In vitro research shows that ginger inhibits CYP2B6 activity. However, this interaction has not been reported in humans.

Theoretically, ginger might increase the levels of CYP2C9 substrates.
In vitro research shows that ginger inhibits CYP2C9 activity. However, this interaction has not been reported in humans.

Theoretically, ginger might increase levels of metronidazole.
In an animal model, ginger increased the absorption and plasma half-life of metronidazole. In addition, the elimination rate and clearance of metronidazole was significantly reduced.

Taking milk thistle with antidiabetes drugs may increase the risk of hypoglycemia.
Clinical research shows that milk thistle extract, alone or along with tree turmeric extract, can lower blood glucose levels and glycated hemoglobin (HbA1c) in patients with type 2 diabetes, including those already taking antidiabetes drugs. Additionally, animal research shows that milk thistle extract increases the metformin maximum plasma concentration and area under the curve and decreases the renal clearance of metformin, due to inhibition of the multi-drug and toxin extrusion protein 1 (MATE1) renal tubular transport protein.

Theoretically, milk thistle might inhibit CYP2B6.
An in vitro study shows that silybin, a constituent of milk thistle, binds to and noncompetitively inhibits CYP2B6. Additionally, silybin might downregulate the expression of CYP2B6 by decreasing mRNA and protein levels.

Theoretically, milk thistle might affect the clearance of drugs that undergo glucuronidation.
Laboratory research shows that milk thistle constituents inhibit uridine diphosphoglucuronosyl transferase (UGT), the major phase 2 enzyme that is responsible for glucuronidation. Theoretically, this could decrease the clearance and increase levels of glucuronidated drugs. Other laboratory research suggests that a milk thistle extract of silymarin might inhibit beta-glucuronidase, although the significance of this effect is unclear.

Theoretically, milk thistle might increase the levels and clinical effects of ledipasvir.
Animal research in rats shows that milk thistle increases the area under the curve (AUC) for ledipasvir and slows its elimination.

Theoretically, concomitant use of milk thistle with morphine might affect serum levels of morphine and either increase or decrease its effects.
Animal research shows that milk thistle reduces serum levels of morphine by up to 66%. In contrast, laboratory research shows that milk thistle constituents inhibit uridine diphosphoglucuronosyl transferase (UGT), the major phase 2 enzyme that is responsible for glucuronidation. Theoretically, this could decrease the clearance and increase morphine levels. The effect of taking milk thistle on morphine metabolism in humans is not known.

Theoretically, milk thistle might decrease the clearance and increase levels of raloxifene.
Laboratory research suggests that the milk thistle constituents silibinin and silymarin inhibit the glucuronidation of raloxifene in the intestines.

Milk thistle might decrease the clearance of sirolimus.
Pharmacokinetic research shows that a milk thistle extract of silymarin decreases the apparent clearance of sirolimus in hepatically impaired renal transplant patients. It is unclear if this interaction occurs in patients without hepatic impairment.

Theoretically, milk thistle might decrease the levels and clinical effects of sofosbuvir.
Animal research in rats shows that milk thistle reduces the metabolism of sofosbuvir, as well as the hepatic uptake of its active metabolite.

Theoretically, the milk thistle constituent silibinin might increase tamoxifen levels and interfere with its conversion to an active metabolite.
Animal research suggests that the milk thistle constituent silibinin might increase plasma levels of tamoxifen and alter its conversion to an active metabolite. The mechanism appears to involve inhibition of pre-systemic metabolism of tamoxifen by cytochrome P450 (CYP) 2C9 and CYP3A4, and inhibition of P-glycoprotein-mediated efflux of tamoxifen into the intestine for excretion. Whether this interaction occurs in humans is not known.

Theoretically, milk thistle might increase the effects of warfarin.
In one case report, a man stabilized on warfarin experienced an increase in INR from 2.64 to 4.12 after taking a combination product containing milk thistle 200 mg daily, as well as dandelion, wild yam, niacinamide, and vitamin B12. Levels returned to normal after stopping the supplement. Although a direct correlation between milk thistle and the change in INR cannot be confirmed, some in vitro research suggests that milk thistle might inhibit cytochrome P450 2C9 (CYP2C9), an enzyme involved in the metabolism of various drugs, including warfarin.

It is unclear if milk thistle inhibits CYP2C9; research is conflicting.
In vitro research suggests that milk thistle might inhibit CYP2C9. Additionally, 3 case reports from the World Health Organization (WHO) adverse drug reaction database describe increased toxicity in patients taking milk thistle and cancer medications that are CYP2C9 substrates, including imatinib and capecitabine. However, contradictory clinical research shows that milk thistle extract does not inhibit CYP2C9 or significantly affect levels of the CYP2C9 substrate tolbutamide. Differences in results could be due to differences in dosages or formulations utilized.

It is unclear if milk thistle inhibits CYP3A4; research is conflicting.
While laboratory research shows conflicting results, pharmacokinetic research shows that taking milk thistle extract 420-1350 mg daily does not significantly affect the metabolism of the CYP3A4 substrates irinotecan, midazolam, or indinavir. However, 8 case reports from the World Health Organization (WHO) adverse drug reaction database describe increased toxicity in patients taking milk thistle and cancer medications that are CYP3A4 substrates, including gefitinib, sorafenib, doxorubicin, and vincristine.

Theoretically, milk thistle might interfere with estrogen therapy through competition for estrogen receptors.
Animal research suggests that a milk thistle extract of silymarin binds to estrogen receptor beta.

Theoretically, milk thistle might interfere with statin therapy by decreasing the activity of organic anion transporting polypeptide 1B1 (OATB1B1) and inhibiting breast cancer resistance protein (BCRP).
Preliminary evidence suggests that a milk thistle extract of silymarin can decrease the activity of the OATP1B1, which transports HMG-CoA reductase inhibitors into the liver to their site of action, and animal research shows this increases the maximum plasma concentration of pitavastatin and pravastatin. The silibinin component also inhibits BCRP, which transports statins from the liver into the bile for excretion. However, in a preliminary study in healthy males, silymarin 140 mg three times daily had no effect on the pharmacokinetics of a single 10 mg dose of rosuvastatin.

Theoretically, milk thistle may induce cytochrome P450 3A4 (CYP3A4) enzymes and increase the metabolism of indinavir; however, results are conflicting.
One pharmacokinetic study shows that taking milk thistle (Standardized Milk Thistle, General Nutrition Corp.) 175 mg three times daily in combination with multiple doses of indinavir 800 mg every 8 hours decreases the mean trough levels of indinavir by 25%. However, results from the same pharmacokinetic study show that milk thistle does not affect the overall exposure to indinavir. Furthermore, two other pharmacokinetic studies show that taking specific milk thistle extract (Legalon, Rottapharm Madaus; Thisilyn, Nature's Way) 160-450 mg every 8 hours in combination with multiple doses of indinavir 800 mg every 8 hours does not reduce levels of indinavir.

Milk thistle may inhibit one form of OATP, OATP-B1, which could reduce the bioavailability and clinical effects of OATP-B1 substrates.
In vitro research shows that milk thistle inhibits OATP-B1. Two case reports from the World Health Organization (WHO) adverse drug reaction database describe increased toxicity in patients taking milk thistle and cancer medications that are OATP substrates, including sorafenib and methotrexate. OATPs are expressed in the small intestine and liver and are responsible for the uptake of drugs and other compounds into the body. Inhibition of OATP may reduce the bioavailability of oral drugs that are substrates of OATP.

Theoretically, milk thistle might increase the absorption of P-glycoprotein substrates. However, this effect does not seem to be clinically significant.
In vitro research shows that milk thistle can inhibit P-glycoprotein activity and 1 case report from the World Health Organization (WHO) adverse drug reaction database describes increased abdominal pain in a patient taking milk thistle and the cancer medication vincristine, a P-glycoprotein substrate, though this patient was also taking methotrexate. However, a small pharmacokinetic study in healthy volunteers shows that taking milk thistle (Enzymatic Therapy Inc.) 900 mg, standardized to 80% silymarin, in 3 divided doses daily for 14 days does not affect absorption of digoxin, a P-glycoprotein substrate.

Theoretically, concomitant use of Terminalia arjuna with anticoagulant or antiplatelet drugs may increase the risk of bleeding in some patients.
In vitro, Terminalia arjuna bark extract inhibits platelet aggregation, decreases platelet activation, and shows antithrombotic properties.

Theoretically, concomitant use of Terminalia bellirica or Terminalia chebula with antidiabetes drugs could affect blood sugar control and increase the risk of hypoglycemia.
Animal and in vitro research shows that Terminalia bellirica and Terminalia chebula fruit and seed extract have hypoglycemic effects.

Theoretically, use of Terminalia chebula may increase the risk of adverse effects from chlorzoxazone.
Animal research shows that enteral administration of Terminalia chebula for 15 days prior to administration of chlorzoxazone increases blood levels of chlorzoxazone and decreases chlorzoxazone clearance. It is speculated that Terminalia chebula reduces the metabolism of chlorzoxazone by inhibiting cytochrome P450 2E1.

Theoretically, use of Terminalia arjuna may increase the levels and clinical effects of CYP2C9 substrates.
In vitro research shows that Terminalia arjuna extract inhibits CYP2C9 enzymes and reduces CYP2C9 substrate metabolism.

Theoretically, use of Terminalia arjuna may increase the levels and clinical effects of CYP2D6 substrates.
In vitro research shows that Terminalia arjuna extract inhibits CYP2D6 enzymes and reduces CYP2D6 substrate metabolism.

Theoretically, use of Terminalia arjuna may increase the levels and clinical effects of CYP3A4 substrates.
In vitro research shows that Terminalia arjuna extract inhibits CYP3A4 enzymes and reduces CYP3A4 substrate metabolism.

Theoretically, use of Terminalia chebula may increase the risk of adverse effects from omeprazole.
Animal research shows that enteral administration of Terminalia chebula for 15 days prior to administration of omeprazole increases blood levels of omeprazole and decreases omeprazole clearance. It is speculated that Terminalia chebula reduces the metabolism of omeprazole by inhibiting cytochrome P450 2C19.

Theoretically, concomitant use of large amounts of red clover might interfere with estrogen therapy.
Red clover contains phytoestrogens which might have estrogenic activity in some people. Theoretically, red clover might compete for estrogen receptors and interfere with estrogen-containing drug therapy.

Theoretically, red clover might increase the risk of methotrexate toxicity.
In a case report, a 52-year-old female receiving weekly methotrexate injections for psoriasis developed symptoms of methotrexate toxicity, including severe vomiting and epigastric pain, after three days of taking red clover 430 mg daily. Toxicity resolved after red clover was discontinued. However, no liver function tests or methotrexate levels were reported.

Theoretically, the phytoestrogens in red clover might interfere with tamoxifen.
In vitro and animal research suggests that genistein, a constituent of red clover, might antagonize the antitumor effects of tamoxifen. However, there is some evidence from an animal study that red clover does not reduce the efficacy of tamoxifen. Until more is known, tell patients taking tamoxifen to avoid red clover.

Although some laboratory research suggests that red clover may have anticoagulant and antiplatelet activity, clinical research has not shown this effect.
In vitro research suggests that genistein in red clover has antiplatelet effects, and historically, red clover was thought to have anticoagulant effects due to its coumarin content. However, some experts state that this is unlikely as most natural coumarins have not been shown to have anticoagulant effects, and their content in red clover is low. Additionally, some clinical research in postmenopausal patients found no effect on coagulation or prothrombin time with the use of red clover flowering tops 378 mg daily for 12 months or red clover isoflavone (Rimostil) 50 mg daily for 2 years.

Theoretically, soy might reduce the clearance of caffeine; however, a small clinical study found no effect.
Red clover contains genistein. Taking genistein 1 gram daily for 14 days seems to inhibit caffeine clearance and metabolism in healthy females. However, this effect does not seem to occur with the lower amounts of genistein found in red clover. A clinical study in healthy postmenopausal individuals shows that taking red clover capsules standardized to contain 60 mg isoflavones twice daily for 14 days does not affect the pharmacokinetics of caffeine.

Theoretically, red clover might increase levels of drugs metabolized by CYP1A2; however, a small clinical study found no effect.
In vitro evidence shows that red clover inhibits CYP1A2. However, a clinical study in healthy postmenopausal individuals shows that taking red clover capsules standardized to contain 60 mg isoflavones twice daily for 14 days does not affect the pharmacokinetics of caffeine, a CYP1A2 probe substrate.

Theoretically, red clover might increase the levels and clinical effects of drugs metabolized by CYP2C19.
In vitro evidence suggests that red clover weakly inhibits CYP2C19. This interaction has not been reported in humans.

Theoretically, red clover might increase levels of drugs metabolized by CYP2C9; however, a small clinical study found no effect.
In vitro evidence suggests that red clover might inhibit CYP2C9. However, a clinical study in healthy postmenopausal individuals shows that taking red clover capsules standardized to contain 60 mg isoflavones twice daily for 14 days does not affect the pharmacokinetics of tolbutamide, a CYP2C9 probe substrate.

Theoretically, red clover might increase levels of drugs metabolized by CYP3A4; however, a small clinical study found no effect.
In vitro evidence shows that red clover might inhibit CYP3A4 isoenzymes. However, a clinical study in healthy postmenopausal individuals shows that taking red clover capsules standardized to contain 60 mg isoflavones twice daily for 14 days does not affect the pharmacokinetics of alprazolam, a CYP3A4 probe substrate.

Theoretically, beet might increase the levels of CYP3A4 substrates.
In vitro research suggests that betanin, the major pigment in beet, competitively inhibits CYP3A4 in a dose-dependent manner similarly to strong CYP3A4 inhibitor ketoconazole.

Beet and beetroot contain nitrates, which can cause vasodilation, potentially leading to lower blood pressure. However, a study published in the European Journal of Clinical Nutrition using concentrated beetroot juice found no significant impact on blood pressure or heart rate in different age groups. Other small clinical studies suggest that while beet consumption might transiently lower blood pressure due to vessel dilation, there's no consistent evidence of a lasting effect. Overall, the theoretical risk of reduced blood pressure due to beet's nitrate content exists, but studies generally indicate a low and temporary impact rather than a sustained decrease.

Theoretically, beet might decrease the levels and clinical effects of CYP1A2 substrates.
In vitro research suggests that beet induces CYP1A2 enzymes.

Theoretically, fennel might increase the risk of bleeding when used with antiplatelet or anticoagulant drugs.

Animal research suggests that fennel oil has antithrombotic and antiplatelet effects.

Theoretically, fennel might decrease the levels and clinical effects of ciprofloxacin.

Animal research shows that fennel reduces ciprofloxacin bioavailability by nearly 50%, possibly due to the metal cations such as calcium, iron, and magnesium contained in fennel. This study also found that fennel increased tissue distribution and slowed elimination of ciprofloxacin.

Theoretically, taking large amounts of fennel might decrease the effects of contraceptive drugs due to competition for estrogen receptors.

Some constituents of fennel have estrogenic activity.

Theoretically, fennel might increase levels of drugs metabolized by CYP3A4.

In vitro research suggests that fennel inhibits CYP3A4 enzyme activity. This effect has not been reported in humans.

Theoretically, taking large amounts of fennel might interfere with hormone replacement therapy due to competition for estrogen receptors.

Some constituents of fennel have estrogenic activity.

Theoretically, taking large amounts of fennel might decrease the antiestrogenic effect of tamoxifen.

Some constituents of fennel have estrogenic activity, which may interfere with the antiestrogenic activity of tamoxifen.

Theoretically, frequent and high doses of rhubarb might increase the risk of hypokalemia when taken with corticosteroids.
Rhubarb has stimulant laxative effects. Overuse of rhubarb might compound corticosteroid-induced potassium loss.

Theoretically, taking rhubarb with cyclosporine might reduce cyclosporine levels.
Animal research shows that co-administration of rhubarb decoction 0.25 or 1 gram/kg with cyclosporine 2.5 mg/kg, decreases cyclosporine maximum plasma concentration and overall exposure levels when compared with taking cyclosporine alone. The authors theorize that rhubarb might reduce cyclosporine bioavailability by inducing of P-glycoprotein and/or cytochrome P450 3A4. However, since rhubarb was administered as a single oral dose and enzyme induction usually occurs after multiple doses, it is possible that cyclosporine absorption was actually reduced via rhubarb's stimulant laxative effects. Also, the composition of the rhubarb decoction was not described.

Theoretically, overuse of rhubarb might increase the risk of adverse effects when taken with digoxin.
Rhubarb has stimulant laxative effects. Overuse of rhubarb might cause potassium depletion, increasing the risk of digoxin toxicity.

Theoretically, frequent and high doses of rhubarb might increase the risk of hypokalemia.
Rhubarb has stimulant laxative effects. Overuse of rhubarb might cause potassium depletion and compound diuretic-induced potassium loss.

Theoretically, concomitant use of rhubarb with potentially hepatotoxic drugs might increase the risk of developing liver damage.
Some animal research suggests that anthraquinones in rhubarb might have hepatotoxic effects. Also, rhubarb use has been linked to at least 24 cases of liver injury, although details on the dose of rhubarb and duration of use in these cases is unclear.

Theoretically, long-term use of anthraquinones from rhubarb might increase the risk of nephrotoxicity when used with nephrotoxic drugs.
The anthraquinone constituents of rhubarb have been shown to induce nephrotoxicity in animal research. Additionally, in a case report, a 23-year old female presented with kidney failure after taking 6 tablets of a proprietary slimming agent (found to contain the anthraquinones emodin and aloe-emodin from rhubarb) daily for 6 weeks and then adding diclofenac 25 mg 4 times daily for 2 days. The authors postulate that the anthraquinone constituents of rhubarb contributed to the renal dysfunction, and the addition of diclofenac, a nephrotoxic drug, led to renal failure. Until more is known, advise patients to avoid taking rhubarb if they are taking other potentially nephrotoxic drugs.

Theoretically, rhubarb might increase the risk for fluid and electrolyte loss when taken with other stimulant laxatives.
Rhubarb has stimulant laxative effects. Concomitant use with stimulant laxatives might compound fluid and electrolyte loss.

Theoretically, excessive use of rhubarb might increase the risk of bleeding when taken with warfarin.
Rhubarb has stimulant laxative effects and can cause diarrhea. Diarrhea can increase the effects of warfarin, increase international normalized ratio (INR), and increase the risk of bleeding. Advise patients who take warfarin not to take excessive amounts of rhubarb.

Theoretically, aloe latex might increase the risk of adverse effects when taken with cardiac glycosides.
Overuse of aloe latex can increase the risk of adverse effects from cardiac glycoside drugs, such as digoxin, due to potassium depletion. Overuse of aloe, along with cardiac glycoside drugs, can increase the risk of toxicity.

Theoretically, aloe gel might increase the risk of bleeding when taken with anticoagulant or antiplatelet drugs.
In vitro research shows that aloe gel can inhibit platelet aggregation. This inhibition was greater than that seen with celecoxib, but less than that seen with aspirin.

Aloe might increase the risk of hypoglycemia when taken with antidiabetes drugs.
Preliminary clinical research suggests aloe gel might lower blood glucose levels and have additive effects when used with antidiabetes drugs. Monitor blood glucose levels closely.

Theoretically, aloe latex might increase the risk of hypokalemia when taken with diuretic drugs.
Overuse of aloe latex might compound diuretic-induced potassium loss, increasing the risk of hypokalemia.

Theoretically, aloe latex might increase the risk for fluid and electrolyte loss when taken with stimulant laxatives.
Due to cathartic laxative effects of aloe latex, concomitant use with other stimulant laxatives might compound fluid and electrolyte loss.

Theoretically, aloe latex might increase the risk of bleeding when taken with warfarin.
Aloe latex has stimulant laxative effects. In some people aloe latex can cause diarrhea. Diarrhea can increase the effects of warfarin, increase international normalized ratio (INR), and increase the risk of bleeding. Advise patients who take warfarin not to take excessive amounts of aloe vera.

Theoretically, aloe might decrease the levels and clinical effects of CYP1A2 substrates.
In vitro research shows that aloe extract induces CYP1A2 enzymes.

Theoretically, taking dandelion root along with anticoagulant or antiplatelet drugs might increase the risk of bruising and bleeding.
In vitro research suggests that dandelion root inhibits platelet aggregation.

Theoretically, dandelion might increase the risk for hypoglycemia when used with antidiabetes drugs.
Laboratory research suggests that dandelion extract may have moderate alpha-glucosidase inhibitor activity and might also increase insulin secretion. Also, in a case report, a 58-year-old woman with type 2 diabetes who was being treated with insulin developed hypoglycemia 2 weeks after beginning to eat salads containing dandelion.

Theoretically, dandelion might increase levels of drugs metabolized by CYP1A2.
Laboratory research suggests that dandelion might inhibit CYP1A2. So far, this interaction has not been reported in humans. However, until more is known, watch for an increase in the levels of drugs metabolized by CYP1A2 in patients taking dandelion.

Theoretically, dandelion might increase the clearance of drugs that are UDP-glucuronosyltransferase substrates.
There is some preliminary evidence that dandelion might induce UDP-glucuronosyltransferase, a phase II enzyme.

Theoretically, through diuretic effects, dandelion might reduce excretion and increase levels of lithium.
Animal research suggests that dandelion has diuretic properties. As diuretics can increase serum lithium levels, the dose of lithium might need to be decreased when taken with dandelion.

Theoretically, dandelion might increase the risk of hyperkalemia when taken with potassium-sparing diuretics.
Dandelion contains significant amounts of potassium.

Theoretically, dandelion might lower fluoroquinolone levels.
Animal research shows that dandelion reduces absorption of ciprofloxacin and can lower levels by 73%. However, this effect has not been reported in humans.

Theoretically, artichoke leaf extract may increase the risk of hypoglycemia when taken with antidiabetes drugs.
A meta-analysis of small clinical studies shows that taking artichoke leaf extract for 8-12 weeks can modestly reduce fasting plasma glucose when compared with placebo.

Theoretically, artichoke leaf extract may increase the risk of hypotension when taken with antihypertensive drugs.
A meta-analysis of small clinical studies in patients with hypertension shows that taking artichoke can reduce systolic blood pressure by around 3 mmHg and diastolic blood pressure by around 2 mmHg when compared with placebo.

Theoretically, artichoke might increase serum levels of drugs metabolized by CYP2B6.
In vitro research shows that artichoke leaf extract inhibits CYP2B6 activity. However, this interaction has not been reported in humans.

Theoretically, artichoke might increase serum levels of drugs metabolized by CYP2C19.
In vitro research shows that artichoke leaf extract inhibits CYP2C19 activity. However, this interaction has not been reported in humans.

Theoretically, chlorella might have additive effects with photosensitizing drugs.
Chlorella has been reported to cause photosensitization. In five case reports, patients who had ingested chlorella exhibited swelling followed by erythematopurpuric lesions on sun-exposed areas of the body. Theoretically, concomitant use with photosensitizing drugs may exacerbate effects.

Theoretically, chlorella might reduce the clinical effects of warfarin.
Chlorella contains significant amounts of vitamin K. There is at least one case report of warfarin therapy becoming sub-therapeutic after initiation of chlorella supplements.

Theoretically, taking fish oil with antihypertensive drugs might increase the risk of hypotension.
Clinical evidence indicates that fish oils can modestly lower blood pressure and might have additive effects in patients treated with antihypertensives.

Theoretically, taking fish oil with contraceptive drugs might decrease the triglyceride-lowering effects of fish oil.
There is some evidence that contraceptive drugs might interfere with the triglyceride lowering effects of fish oils.

Taking fish oil with cyclosporine might increase levels and adverse effects of cyclosporine.
In kidney transplant recipients on a general immunosuppressive regimen, taking omega-3 fatty acids daily seems to increase peak blood levels of cyclosporine when compared with placebo. This increase was as much as 20% after one month. However, the area under the curve was not significantly affected.

Theoretically, taking fish oil with orlistat might decrease the absorption of fish oil fatty acids.
Orlistat binds lipase in the gastrointestinal tract and reduces fat absorption. Theoretically, taking fish oil with orlistat might decrease absorption of fish oil fatty acids. To avoid this potential interaction, recommend separating administration of orlistat and fish oil by at least 2 hours.

Taking fish oil with sirolimus might increase levels and adverse effects of sirolimus.
Pharmacokinetic research shows that omega-3 fatty acids increase exposure to sirolimus in kidney transplant patients on a calcineurin inhibitor-free immunosuppressive regimen. A 25% dose reduction in sirolimus was required to keep patients within the expected trough-concentration window. Researchers hypothesize that this may be due to inhibition of cytochrome P450 3A4 (CYP3A4) by fish oil, although this has not been confirmed in clinical research.

Taking fish oil with tacrolimus might increase levels and adverse effects of tacrolimus.
In a small group of patients, taking fish oil 2.6 grams (Omacor) daily for 4 weeks increased the 8-hour area under the curve of tacrolimus by 25% when compared with baseline. Peak levels were increased by approximately 22%. Researchers hypothesize that this may be due either to an increase in bioavailability or to inhibition of cytochrome P450 3A4 (CYP3A4) by fish oil, although this has not been confirmed in clinical research.