rhb-
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!
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DrDave
I take my nasal spray all year because I am allergic to dust and animal hair too. I only need tablets for the summer though...
I find it really interesting how different people get on better with one drug or another, or various combinations. It’s the interaction of individual genetics and the different spectrum of allergens in different areas. As with every area of medicine, there is no one size fits all, and it’s always a question of trial and error. It annoys me that many (most) doctors don’t admit that there are things they don’t know.
Doesn’t change the utter torture of peak hayfever season - hope everyone is coping ok!