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Limited evidenceMen's health

Bulbine Natalensis

A South African herb sold as a testosterone booster on the strength of rat studies. There are no human trials at all, and the same rat work flagged organ toxicity at higher doses.

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What the science says

  • Testosterone in rats Limited evidence

    Rat studies from a single laboratory reported that the aqueous stem extract raised serum testosterone and increased sexual behaviour over 14 days. All of the testosterone data come from rodents; no human trial has ever been published.

  • Drug interaction risk Limited evidence

    Laboratory work showed that Bulbine natalensis and its knipholone constituents inhibit CYP3A4 and CYP2C9, the enzymes that clear a large share of prescription drugs. This is in-vitro evidence, but it is the most concrete human-relevant finding available for the plant.

Dosage & safety

Studied doseNo human dose has been established. Products typically supply 325–650 mg of extract per day, which is extrapolated from rodent studies rather than tested in people.
SafetyThe same rat studies that reported androgenic effects also found raised liver and kidney markers and reduced organ weights at higher doses. Combined with the in-vitro CYP3A4/CYP2C9 inhibition, this is a plant to avoid if you take any prescription medication, have liver disease, or are pregnant or breastfeeding.

How to take it

TimingNo human dosing schedule exists, so there is nothing meaningful to say about timing.
With food?Take with food if you use it at all, to reduce stomach upset.
Worth knowingThe rodent studies that generated the testosterone claims also showed raised liver and kidney markers at higher doses, so if you use it, get liver enzymes checked rather than assuming it is inert.

Interactions

With medications

  • any prescription medication metabolised by CYP3A4 or CYP2C9

    The extract inhibits both enzymes in laboratory tests, which could raise drug levels, and no human study has checked whether it does. do not take it if you are on prescription medication

Well-established interactions only — this is not a complete list. Always tell your doctor and pharmacist what you take.

Frequently asked questions

Does bulbine natalensis raise testosterone?

Only in rats: bulbine natalensis raised testosterone in rodent studies from a single laboratory, and no human trial has ever been published. The evidence grade is limited.

Is bulbine natalensis safe?

The same rat studies that reported androgenic effects of bulbine natalensis also found raised liver and kidney markers and reduced organ weights at higher doses. Avoid it if you have liver disease or are pregnant or breastfeeding, and get liver enzymes checked if you use it.

Can you take bulbine natalensis with prescription drugs?

No. In laboratory tests bulbine natalensis inhibits CYP3A4 and CYP2C9, the enzymes that clear many prescription drugs, which could raise drug levels, so do not take it if you are on prescription medication.

What is the dose of bulbine natalensis?

No human dose of bulbine natalensis has been established. Products typically supply 325–650 mg of extract per day, extrapolated from rodent studies rather than tested in people.

Scientific references

Related in Men's health

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