Route Of Exposure

Allergen Exposure

Poppy is an annual herb native to south-eastern Europe and western Asia. There are wild and cultivated varieties. The species is cultivated extensively in many countries, especially in Asia and Central and South America.

The plant can reach a height of 1.2 m. It can have white, pink, red, or purple flowers and is an important ornamental. Seeds range in colour from white to blue-black. The seeds are rather small, but there are large numbers of them contained in capsules 3 cm or more in diameter, and so they are easy to harvest and utilise. They are often eaten as flavouring but can also be processed as drugs, including the illicit drugs opium and heroin.

Poppy seeds are employed raw or cooked. They are used as flavouring in cakes, bread, fruit salads, etc. The crushed and sweetened seeds are a filling in certain crêpes, strudels, and other pastries. The seeds are perfectly safe to eat, containing very little if any of the narcotic principles; however, they have been reported to cause false positives on drug tests. The seeds are highly nutritious. A high-quality edible drying oil, also not narcotic, is obtained from the seed and makes a good substitute for olive oil. The young leaves, raw or cooked, are edible and probably do not contain narcotic principles, but caution is advised.

The latex from the unripe green seed contains a wide range of alkaloids (including morphine, opium, codeine, noscapine, papaverine, thebaine and narcotine) and yields valuable medicines, especially useful in bringing relief from pain. But this substance (and especially the opium and morphine it contains) can cause addiction and so should be treated with extreme caution and used only under the supervision of a qualified practitioner.

Seeds of the plant are not always apparent or noticed when used in bakery products. Poppy seed is sometimes used as a colouring in cough syrups and other products.

Poppy seed is sometimes used for its oil, which can also be a "hidden allergen". The Poppy seeds and the fixed oil that can be expressed from them are not narcotic, because the seeds develop after the capsule has lost its opium-yielding potential. However, the narcotic principles are still present and may be detected in urine sampling.

Poppy oil is used for lighting, and in the manufacture of paints, varnishes, and soaps. Poppy latex features in a number of medicinal products.

Clinical Relevance

Allergen description

The following allergens from this plant have been isolated:

In a study of sera of 11 Poppy seed-allergic patients, specific IgE from the sera of 10 bound to a 45 kDa, 4 to a 34 kDa, 5 to a 17 kDa, 5 to a 14 kDa, and 3 to a 5 kDa protein. Individual IgE binding to proteins of 20, 25, 30 and 40 kDa was also seen. The 40 and 45 kDa allergens were glycoproteins and contained IgE binding carbohydrate moieties. Cross-reacting homologues of pollen allergens, including Bet v 1 and profilin, were detected in Poppy seed extract. In individuals with occupational asthma from working with shells of P. somniferum, a major protein band with an estimated size of 52 kDa was detected.

Cross Reactivity

An extensive cross-reactivity among the various individual species of the genus and family, including the Californian poppy (Eschscholzia californica), the Mexican poppy (Argemone mexicana) and celandine (Chelidonium majus), could be expected.

Poppy seed contains homologues of Bet v 1 and profilin, which indicates the possibility of cross-reactivity with other plants containing these panallergens. Nine of 11 patients in a study of allergenicity to Poppy seed showed concomitant IgE binding to allergens of Birch, Mugwort or grass pollen in laboratory tests. They reported characteristic seasonal symptoms.

Allergy to Kiwi, Poppy seeds, and/or Sesame seeds has been reported to occur often in patients with a simultaneous sensitisation to nuts and flour. In a study investigating this association, the degree of cross-reactivity among Kiwi, Sesame seeds, Poppy seeds, Hazel nuts, and Rye grain was found to be very high in the patients studied. The existence of both cross-reacting and unique allergens was observed; however, the cross-reacting and unique allergens could have been different for different patients.

A study describes 3 patients with severe immediate-type allergic reactions to Poppy seed, all of whom had serum showing IgE antibody binding specific for Sesame seed. The authors considered that this might be due to a cross-reactivity to similar allergens.

In a report of a 17-year-old female with an apparent allergic reaction from ingestion of a Poppy seed cake, a novel allergen causing cross-sensitisation to Buckwheat was described.

Clinical Experience

IgE-mediated reactions

Poppy seed commonly induces symptoms of food allergy in sensitised individuals, which may be confirmed by SPT and IgE antibody determination. It has been suggested that the prevalence of Poppy seed allergy is increasing as a result of the increased number of vegetarian and ethnic dishes.

Immediate-type allergic reactions range from mild local symptoms to severe anaphylactic reactions, and may involve the gastrointestinal, respiratory or skin systems. A patient who experienced an immediate-type hypersensitivity reaction against Poppy seed described symptoms of swelling of the oral mucosa, vomiting, respiratory distress, and urticaria. Poppy seed-specific IgE was demonstrated.

Other studies have described similar severe immediate-type reactions to Poppy seed; these studies include a report of 3 patients in whom SPT and IgE antibody test were positive. Immediate-type allergy caused by Poppy seed in a 52-year-old man was described. Symptoms included epigastric pain, angioedoema, and respiratory distress a few minutes after eating Poppy seed cake. SPT and IgE antibody test were positive. A 17-year-old female had an apparent food-allergic reaction after ingestion of a Poppy seed cake. Laboratory investigation led to the identification of a novel cross-sensitisation with Buckwheat.

Anaphylaxis and food-dependant exercise-induced anaphylaxis have been reported. Food-dependant exercise-induced anaphylaxis was described in a 46-year-old man who had experienced 4 episodes of generalised urticaria, all occurring within 1 hour after ingestion of a Poppy seed cake. These episodes occurred only in combination with exercise, although he had been eating this cake every Friday for about a year. SPT for Poppy seed was positive and allergen-specific IgE was 13.4 kUA/l. Oral challenges without exercise were negative. On follow up, the patient reported that he had continued to eat Poppy seed cake every Friday, but that only in combination with gardening had generalised urticaria occurred.

A study described immune and non-immune hypersensitivity reactions to Poppy seed in a 21-year-old woman and a 32-year-old man, in both of whom life-threatening symptoms and signs of anaphylaxis developed after consumption of Poppy seeds in various situations, e.g., after consumption of a roll with Poppy seeds on it, and of a cake prepared on a moulding board on which Poppy seed paste had previously been squeezed. The female patient was reported to have a history of atopy, and in her case skin reactivity was detected to a range of pollen allergens and to Hazel nuts, whereas SPT for various allergens was negative for the male. In the female, the IgE antibody levels were raised for Celery and nut mixture but negative for Poppy seed, whereas in the male the IgE antibody levels for Poppy and nut mixture were both raised (Class 2). In the male patient, among SPT with topical anesthetics and narcotic analgesics derived from Poppy, tests were positive for xylocaine and codeine. The authors concluded that hypersensitivity to Poppy seed may occur through IgE-dependent or non-immune mechanisms, and that a history of atopy is not completely determinant.

Inhalation of Poppy seed resulting in erythema, angioedema, conjunctivitis, and dyspnoea in a 16-year-old boy was described. Skin reactivity was present for Poppy seed, Hazel nut, and Chickpea. IgE levels for Poppy seed, Hazel nut, and Peanut were 3.36 kUA/l, 1.5 kUA/l, and 6.17 kUA/l, respectively. This is the first report on inhalant allergy to Poppy seed.

Allergic contact dermatitis and contact urticaria have been reported to closely related family members, Papaver rhoeas and Papaver nudicaule (Icelandic poppy).

Other reactions

IgE reactions have also been reported to Poppy shells, which contain the seeds. Six of 28 workers in a pharmaceutical factory producing morphine and extracting other alkaloids from shells of Papaver somniferum were found to have clinical symptoms of sensitisation to Poppy. Skin reactivity was demonstrated. A bronchial provocation test was found to be positive for 4 workers, and in all of these cases IgE antibodies were demonstrated to an aqueous extract of P. somniferum. Histamine release tests using the same antigen were also positive in the 4 samples from sensitised patients. A major protein of around 52 kDa was isolated. These findings suggest that P. somniferum allergy is mediated by an IgE mechanism and not by a pharmacological or toxic effect of the alkaloids or polyphenols.

This plant contains a number of very toxic compounds, many of which are extracted and used as pain killers, etc. They are also used to make various narcotic drugs, which do not all fit the stereotypes of highly refined “street drugs”. Danish Poppy capsules contain 3-5 mg morphine per capsule, and the content of morphine in opium exuded from the capsules may amount to 24%. This has resulted in misuse, as both fresh and dried Poppy capsules can yield “opium tea”. During the period 1982-1985, 7 casualties occurred among drug addicts in Denmark that were solely or partly caused by these Opium capsules. A patient presenting with dependence on Opium poppy tea has also been reported. But Poppy tea drinking, although previously described in certain parts of the UK, rarely presents as a dependence syndrome.

Because Poppy seed may be an ingredient in ordinary confections, caution is warranted in environments with drug testing. In a study in which 9 volunteers ingested cake containing Poppy seed, several urine specimens contained morphine with concentrations higher than 1 microg/ml, and the peak values were approximately 10.0 µg/ml. Because the International Olympic Committee has set a cut-off for morphine at 1 µg/ml, athletes could fall foul of testing after consumption of products containing Poppy seeds.