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Very thorough response, thanks!
I used to be wiped out for months by it, now I get a few bad days a year. This began since doing more trail runs on paths that are nettle heavy around 2016 & now allotment work too amongst nettles so get regular stings.
I guess most likely maybe it is simply correlation or placebo, not direct cause but whilst something or nothing about is effective either way I'll stick with it.
rhb-
That’s really interesting, as you say possibly correlation or placebo, but maybe there is something else going on.
Another fascinating thing about allergies is how they change over time. Many allergies are worse in childhood and improve, or disappear, during adolescence. The opposite also happens and people can develop allergies in young adulthood or middle age, sometimes mild like hayfever but also life threatening allergies to food or drugs. We don’t know why this happens. There are also almost unbelievable phenomena such as people becoming allergic to red meat after being bitten by a type of tick. There’s a huge amount in medicine that we don’t understand at all.
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Conversely I've been doing a lot more off-road riding than I would normally (and getting enough nettle stings that my shins still tingle a few days later), and my hayfever is worse than it has ever been. Suspect there's pretty good correlation between razzing around in the undergrowth, and kicking up pollen into my sinuses. But I'm now going to promote that nettles cause hayfever. KILL ALL THE NETTLES!
DrDave
user20714
If it works for you, that’s great, but I won’t be trying it.
Nettle stings contain histamine and other active amines like serotonin and choline, which are injected very superficially into the skin. The effect is very local and no histamine from the stings is absorbed into the bloodstream, otherwise the reaction to a nettle sting would be much more severe. The itching and weal from a nettle sting, with a raised white centre surrounded by redness, is caused by the histamine.
Histamine is also a mediator of allergy, it is released from some types of white blood cell in response to allergens. In hayfever it is released from cells in the nose and eye and contributes to the redness, swelling and increase in secretions. Again, this is a very localised effect. Antihistamine medicines block the effect of histamine on nearby tissues and reduce this reaction. In more severe allergies, the release of large amounts of histamine and other substances into the bloodstream is what causes anaphylaxis, which causes dilation of blood vessels leading to circulatory collapse, as well as bronchospasm (constriction of airways) and other effects. In systemic allergy the same weals, also called hives or urticaria, are sometimes seen on the skin. This is a result of systemic release of histamine causing a skin reaction at a site remote from the causative allergen.
So, if nettle stings had an appreciable systemic effect, you might expect to see low blood pressure, wheezing etc. and urticaria at sites away from the sting. You don’t see this because the local dose from a nettle sting is so tiny.
As far as I can understand the only connection between the two processes is the involvement of histamine. I don’t see how there is any plausible way that a very tiny, local dose of histamine on the skin from a nettle sting could have any prolonged effect on tissues at other sites in the body ie. nose and eyes. And if it did have a systemic effect, you would see a worsening of hayfever symptoms, not an improvement. It’s not at all like a vaccine, in which a systemic dose of a pathogen causes the production of antibodies. Adaptive immunity, the process of antibody production, is not involved in allergy. The mechanism is entirely different.
I’ve done a bit of reading around the idea this evening, and have seen a few tabloid stories but no serious explanation of why it might work.
However, if it works for some people, that’s very interesting, and there may be another process occurring that we don’t know about. The placebo effect may be playing a part. A few nettle stings won’t do any serious harm anyway, so why not give it a try? I’m not convinced though!