Cistus Incanus
A polyphenol-rich Mediterranean rock rose with one placebo-controlled cold trial from 2009 that has never been replicated, plus cell-culture antiviral data that gets over-extrapolated into systemic immune claims.
What the science says
- Upper respiratory tract infection symptoms Limited evidence
In a randomised, placebo-controlled trial of 160 patients with common cold, lozenges of the Cistus extract CYSTUS052 produced a significantly greater fall in subjective symptom score than placebo, and C-reactive protein dropped significantly in the treatment group. That is the entire clinical database: one manufacturer-linked trial, never independently replicated in the 15+ years since, with effect sizes not clearly quantified in the published abstract.
- Antiviral activity is a surface effect, not a systemic one Limited evidence
The CYSTUS052 polyphenol extract blocked influenza virus in cell culture without cytotoxicity and without inducing viral resistance, apparently by binding viral surface proteins and physically preventing cell attachment. That mechanism fits a lozenge coating the throat — it is not a reason to expect systemic antiviral effects from swallowing tea, because polymeric polyphenols of this size are barely absorbed.
- Lyme, biofilms and 'detox' claims Limited evidence
Cistus incanus appeared as one of seven active hits in a 2020 in-vitro screen against stationary-phase Borrelia burgdorferi at 1% extract concentration. There is no human trial in Lyme disease, and the popular claim that Cistus tea 'chelates heavy metals' or 'dissolves biofilms' in the body has no clinical support at all.
Dosage & safety
How to take it
Interactions
With other supplements
- iron supplements
The high tannin content markedly reduces non-heme iron absorption. separate by at least 2 hours
Well-established interactions only — this is not a complete list. Always tell your doctor and pharmacist what you take.
Frequently asked questions
Does Cistus incanus help with colds?
The evidence is limited to one trial: in 160 people with a cold, Cistus incanus (CYSTUS052) lozenges reduced symptom scores more than placebo. That manufacturer-linked trial has never been independently replicated.
Does Cistus tea boost immunity or fight viruses in the body?
Not shown. Cistus incanus blocks influenza virus in cell culture by binding the virus surface, which fits a lozenge coating the throat, but its large polyphenols are barely absorbed. There is no reason to expect systemic antiviral or immune effects from drinking Cistus tea.
Does Cistus incanus detox heavy metals or help Lyme?
There is no clinical support: Cistus incanus appeared only as a hit in a test-tube Borrelia screen, and no human trial has tested it in Lyme disease. The claims that Cistus tea chelates heavy metals or dissolves biofilms are unsupported.
Does Cistus tea affect iron absorption?
Yes. Cistus incanus tea is high in tannins, which meaningfully impair non-heme iron absorption, so keep it at least two hours away from iron supplements and iron-rich meals. This matters most if you are anaemic or vegetarian.
Scientific references
- Cistus incanus (CYSTUS052) for treating patients with infection of the upper respiratory tract. A prospective, randomised, placebo-controlled clinical study
- A polyphenol rich plant extract, CYSTUS052, exerts anti influenza virus activity in cell culture without toxic side effects or the tendency to induce viral resistance
Where to buy
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Related in Immunity
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- Andrographis Moderate evidence