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Juniper berry toxicity.

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Juniper berries aren't that irritating to the kidneys.

I've taught for years that you can't use loads of juniper berries, because they irritate the kidneys. I haven't muttered that caution with juniper for the last few years, though, because I remembered a post about it on a list for herbalists. This one:

I think the rumors of Juniperus spp (juniper) causing kidney problems are greatly exaggerated and based on an even worse insult than the Melissa studies being extrapolated to humans. Read Tisserand's discussion of it in Essential Oil Safety. The studies suggesting renal problems actually used Juniperus sabina (savin). Look at the existing rat study (yes, they're rats) in which they practically drowned the poor buggers in Juniperus communis essential oil [link below] and guess what -- no renal damage whatsoever. Anyhow, I think it is absolutely indicated in renal infections as a combination inflammation modulator and antimicrobial, and I think it's diuretic effects wouldn't somehow be so powerful as to damage the kidneys. But I could be wrong.
That being said, I've never had a patient with pyelonephritis, so I don't actually know from personal experience what would happen. But I would include Juniperus tincture in their herbal formula, in reasonable doses.

Urologically yours,
Eric Yarnell, ND, RH(AHG)
Seattle, WA"

So there you have it. All the fuss is because savine is a juniper, too. It's toxic, as is its oil:

"Savin is emmenagogue, diuretic, diaphoretic, and anthelmintic. In large doses it will produce gastro-enteritis. Care must be taken in its administration, as it has, in several instances, produced fatal results. It should never be given when there is any general or local inflammation present, and it should never be used during pregnancy,"
(King's American Dispensatory)

"Oil of savine is a powerful irritant to the mucous tissues, and powerfully deranges the nervous system. It may induce gastro-intestinal inflammation, vesical tenesmus and strangury, congestion of the pelvic organs, fever, mental excitation and intoxication, coma, and death."
(King's American Dispensatory)

And "normal" juniper oil (Juniperus communis) isn't toxic, even in high doses, in rats. Note, a juniper tincture contains almost the same constituents as oil of juniper:

"The nephrotoxicity of juniper oil ... was evaluated in ... rats after oral administration. Two ... slightly different oil batches were tested for 28 days with 100, 333 or 1000 mg ... resp. 100, 300 or 900 mg ... juniper oil/kg. Additionally terpinene-4-ol ... was tested in a dosage of 400 mg/kg. Neither of the tested substances induced changes in function or morphology of the kidneys at the tested doses, and they were revealed to be nontoxic."
Schilcher H, Leuschner F., The potential nephrotoxic effects of essential juniper oil., Arzneimittelforschung. 1997 Jul;47(7):855-8.

Related entries: Picking juniper berries - Using juniper berries - Juniper salmon


excerpt from a writing project i'm working on....

"Analyses of the literature and studies of juniper essential oil indicate that toxicity concerns are based on case reports likely involving misidentified or adulterated juniper essential oil (Bone 1995; ESCOP 2003; Schilcher et al. 1993; Schilcher and Heil 1994; Wichtl 2004; Yarnell 2002). Some of these analyses suggest that juniper should be used with caution in cases of acute kidney inflammation (Bone 1995; Weiss and Fintelmann 2000; Yarnell 2002)."

Thanks for that, Zoe!

Having been taught by Hein Zylstra that we should be very cautious with the use of Juniper I have never tended to use it much with my clients and if I did include it in a diuretic mixture it would be 5ml p.w.
However I used to employ an assistant and she purchased some tablets for cystitis in the local health store. When I examined the ingredients and noticed Juniper was one of them, I told her of my concern that this herb was included in a n over the counter product. She then commented that she had been having pains in her kidney area since taking the tablets.

That's worrying. Did she rechallenge?

I'd avoid anything that gives pain in the kidneys.