|Milk Thistle Dosage
October 18, 2011
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Milk Thistle Dosage Forms
Milk thistle is commercially in the dosage forms of: capsules, liquid extract, tincture and silymarin
An optimal dosage for milk thistle preparations has not been established. Most capsules of standardized dried
herb (each capsule contains about 120 - 140 mg silymarin) and most milk thistle extract is standardized to 80%
silymarin. However, capsules of higher dosages, such as 200 mg and 300 mg are also available. According to
WebMd.com (October 20, 2011), A specific combination of milk thistle and several other herbs has been used
in a dose of 1 mL three times daily for dyspepsia and silymarin 200 mg three times daily has been used in
combination with other treatment for diabetes.
Effects of High Dosages of Milk Thistle
Human studies of silymarin have shown minimal adverse effects in multiple large, blinded, placebo-controlled,
randomized studies. Silymarin is well tolerated, with only rare reports of a mild laxative effect. Mild allergic
reactions have been seen at high dosages (>1,500 mg /day), although the details of these allergic reactions
were not reported. A recent case report from Australia described a reaction to a milk thistle extract that
included intermittent episodes of sweating, abdominal cramping, nausea, vomiting, diarrhea, and weakness. All
symptoms resolved when the silymarin was discontinued.
According to the German Commission E, there are no reported side effects with milk thistle within the
recommended doses. One human dosing study reported nausea, heartburn, and dyspepsia in patients treated
with only dosage of 160 mg/day, dyspepsia in patients treated with a dosage of 240 mg/day, and postprandial
nausea and meteorism in patients treated with a dosage of 360 mg/day. None of these side effects were dose
Milk Thistle Ingredient Dosage and Toxicity
Silymarin has been well tolerated in high doses. Silymarin has been used in pregnant women with intrahepatic
cholestasis at doses of 560 mg/day for 16 days, with no toxicity to the patient or the fetus. The published data
on silymarin use in children focuses on intravenous doses of 20 to 50 mg/kg body weight for mushroom
poisoning. Silymarin has also proved nontoxic in rats and mice when administered in doses as high as 5,000
mg/kg body weight. Rats and dogs have received silymarin at doses of 50 to 2,500 mg/kg body weight for a 12-
month period. Investigations, including postmortem analyses, showed no evidence of toxicity.
Milk Thistle Dosage Adjustment
Oral administration of milk thistle (Dosage 200 mg, a clinically relevant dose, 3 times per day) had no significant
effects on the pharmacokinetics of irinotecan. The authors concluded that the recommended doses of milk
thistle are too low to affect activity of CYP3A4 or UGT1A1 enzyme pathways. However, milk thistle may still
interact with other drugs or at higher dosages. Consult with your doctor if you require a dosage adjustment for
Theoretically, milk thistle may also interact adversely with chemotherapy drugs that exert their cytotoxic effects
through the generation of free radicals. Silymarin and its metabolite inhibit P-glycoprotein–mediated cellular
efflux, leading to the potentiation of doxorubicin cytotoxicity. No trials have been performed to support or
negate these theoretical considerations. No effects on indinavir and alcohol pharmacokinetics have been
observed. Enhancement of antiarrhythmic effects of amiodarone in rats has been observed.
Milk Thistle (PDQ) National Cancer Institute Online Publication, October 20, 2011
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manufacturer, you should be able to find the contact information on the label.
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effects of a supplement or a drug product. Finally, please, do not transfer the article to other website. Thank
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