Itchy eyes or a rash after trimming plants, or a runny nose near a hemp field in late summer? Hemp and cannabis (Cannabis sativa) can trigger IgE sensitisation through pollen, smoke and handling the plant, and one of its proteins links it to several plant foods. Our test checks IgE to hemp and to its lipid transfer protein Can s 3, as part of 300 allergens and allergen components.
Hemp and cannabis are the same species, Cannabis sativa. Industrial hemp is grown for fibre, seed and oil; other varieties are grown for cannabis. Male plants are wind-pollinated and release a lot of light pollen in late summer.
Pollen is only one route. People also meet the plant's proteins by touching leaves and flowers, by working with dried plant material, and through smoke. As cannabis use and home growing have become more common, reports of cannabis sensitisation have grown too.
Reports range from hay fever symptoms near flowering plants, to itchy skin, redness or hives after handling the plant, to a cough or tight chest after smoke.
Some people sensitised to hemp also report itching or swelling in the mouth after eating certain fruits, vegetables or nuts (see below). Swelling of the lips, tongue or throat, trouble breathing or feeling faint after eating is an emergency. Call 112 (EU) or your local emergency number. Do not wait for a test.
Can s 3 is a lipid transfer protein (LTP). LTPs are sturdy plant proteins that survive heat and digestion better than many others, and similar ones are found in peach, apple, tomato, citrus and many nuts.
That is why doctors in Belgium, the Netherlands and Spain have described a cannabis-fruit-vegetable pattern: people sensitised to Can s 3 who also react to LTP-rich foods. Because LTP reactions to food are not always mild, a result that shows IgE to Can s 3 is worth discussing with a doctor.
From a finger-prick sample, the lab measures IgE to the two hemp markers below as part of 300 allergens and allergen components. Other LTPs, such as peach (Pru p 3), apple (Mal d 3), hazelnut (Cor a 8), walnut (Jug r 3), peanut (Ara h 9) and wheat (Tri a 14), are on the same report, so you can see whether an LTP pattern runs through your results.
A positive result means your blood shows IgE to hemp. That is sensitisation, not a diagnosis. Each value gets a class from Negative to Very high, to discuss with a doctor.
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One finger-prick sample checks IgE to 300 allergens and allergen components, from birch and peanut to cat and house dust mite. Post it to the lab, and about 5 days after it arrives you get a value for every one. Our plain-English guide shows you how to read them. €399 in total, €1.33 per allergen.
Yes, cannabis allergy is described in the medical literature. People report hay fever symptoms, skin reactions after handling the plant, breathing symptoms after smoke and, in some cases, reactions to certain foods. A blood test shows whether you have IgE to hemp; a doctor puts that together with your symptoms.
Hemp contains a lipid transfer protein, Can s 3. Peach, tomato, apple, citrus and many nuts contain similar LTPs. IgE made against one can recognise the others, which is called cross-reactivity.
It can be locally. Industrial hemp is grown in the Netherlands, Germany and elsewhere, and male plants release pollen in late summer. For many people, though, the main exposure is handling plants or smoke rather than pollen in the air.
No. The panel measures IgE to hemp plant proteins and to Can s 3. Hemp seeds and oils are a separate question. If you have reacted to a hemp food, tell a doctor.
