Allergen Exposure

Probably native to the tropics, these peppers produced flavourings that became known in the West through the spice trade. They are now grown mainly in China, Japan, Malaya, the Caribbean, Mexico, Hawaii, the Middle East, and Spain. The spices/condiments are important elements of several national cuisines.

In the Solanaceae family, C. frutescens includes chilli peppers or cayenne pepper. Chilli peppers tend to be eaten in very small amounts as spices or condiments, due to their strong flavours; as opposed to sweet pepper, which is usually used as a vegetable.

Not known in the wild, chilli peppers are grown in cultivated beds. The flavour can range from pungent to hot, the colour from bright orange-red to deep blood-red. Peppers are a good source of dietary antioxidants, as well as other widespread compounds (flavonoids, phenolic acids, carotenoids, vitamin A, ascorbic acid, tocopherols), and also contain specific constituents such as the pungent capsaicinoids (capsaicin, dihydrocapsaicin, and their analogues).

The fruits of this plant are usually sold under the catch-all name of chillies. The substance in the pepper which cannot be vaporised – the non-volatile phase – accounts for the hot taste of the chilli pepper.

C. frutescens pods may be used as a seasoning and garnish for a plethora of savoury dishes. Sauces combine the chillies and their derivatives with tomatoes, vinegar and spices; some are thickened with cornstarch, and some take years to ferment and mature.

The fruit of these peppers may be used as a herbal remedy for a variety of conditions, including as an ingredient in a topical capsicum-based product for the treatment of lower back pain and otitis media. The oleoresin of capsicum may be used as a riot control agent.

Capsaicin is a major pungent ingredient of capsicum fruits such as green and red peppers. Capsaicin is used as a food additive or as an over-the-counter topical agent for treatment of post-herpetic neuralgia, diabetic neuropathy, and arthritis. (1)

Allergen Description

No allergens have been characterised.

The following allergens have been characterised from C. annuum (Sweet pepper/Paprika f218). C frutescens may contain similar allergens:

Cap a 1, a thaumatin-like protein. (2, 3)

Cap a 2, a profilin. (3, 4, 5)

Other allergens detected include a Bet v 1 homologue, (4) an ascorbic acid oxidase, (6) a 1,3-beta-glucanase, (6) and a chitinase. (7)

A profilin and Bet v 1 have been detected in sweet pepper. Examination of a variety of horticultural strains of sweet peppers demonstrated the presence of profilin in all and of Bet v 1 in 50%, suggesting that sweet peppers must be considered potentially dangerous for Bet v 1-sensitised and profilin-sensitised patients. In 4 of 8 horticultural strains of sweet peppers, a homologue of the osmotin-like protein P23 from tomatoes was responsible for substantial IgE binding. (4) The P23 allergen appears to be a 23 kDa allergen. Other uncharacterised allergens detected were of a higher molecular weight. (8)

A beta-1,4-glucanase (a cell wall-associated enzyme believed to function in fruit ripening) has been isolated from sweet pepper. (9) In other plants this enzyme has been shown to have allergenic activity, but its allergenic relevance in sweet pepper has not yet been determined.

In a study that demonstrated IgE reactivity to multiple spice allergens in workers exposed to high levels of inhalable spice dust, allergens of approximately 40 and 52 kDa were demonstrated in chilli pepper. (10)

Potential Cross Reactivity

Extensive cross-reactivity between the different individual species of the genus could be expected, but in fact does not occur frequently. (11)

Cross-reactivity to other plants containing the panallergens profilin and Bet v 1 could be expected to occur frequently. Patients with allergy to sweet pepper and associated pollinosis show a high frequency of IgE reactivity to profilin. (12) Although some strains of sweet pepper contain a homologue of the osmotin-like protein P23 from tomatoes, which is responsible for substantial IgE binding in vitro, (4) the clinical relevance of this allergen has yet to be determined.

A high frequency of sensitisation to sweet pepper has been reported in latex-allergic patients. (13, 14) Approximately 30-50% of individuals who are allergic to natural rubber latex show an associated hypersensitivity to some plant-derived foods, especially freshly consumed fruits. This association is called latex-fruit syndrome. An increasing number of plant sources, such as avocado, banana, chestnut, kiwi, peach, tomato, potato and sweet pepper have been associated with this syndrome. Several types of proteins have been implicated: class I chitinases, which cross-react with hevein, and a beta-1,3-glucanase. (12, 15) Children allergic to natural rubber latex often show allergenicity to sweet pepper. (16)

By ELISA-inhibition assays, a partial cross-reactivity was found among IgE-binding components from paprika and mace, but the clinical relevance of this has not been determined. (17)

Clinical Experience

IgE-mediated reactions

Sweet pepper or spices made from Sweet Pepper may induce symptoms of food allergy, rhinitis and contact dermatitis in sensitised individuals. (4, 18, 19, 20, 21) Urticaria as a result of contact with paprika has been documented. (22) Chilli pepper has been implicated as a cause of eosinophilic esophagitis. In a study of 16 men and 7 women aged 18-57, nineteen had serum IgE specific for one or more food-associated allergens (median, 5 foods), with wheat, tomato, carrot, and onion identified most commonly. Sensitisation to chilli pepper was documented in 2 (9%). (23) Adverse reactions (similar to those experienced in reaction to Sweet Pepper) may be expected.

A 27-year-old individual who developed rhinitis and asthma symptoms when preparing a spiced sausage was reported. Skin-specific IgE was detected to paprika, coriander and mace, but not to other ingredients of sausage. Serum-specific IgE to paprika, coriander and mace was demonstrated. Specific bronchial inhalation challenges showed an immediate asthmatic reaction to extracts from paprika, coriander and mace, with a maximum fall in FEV1 of 26%, 40% and 31% respectively, and with no late asthmatic reactions. (17) A severe asthma attack in a patient with premenstrual asthma was attributed to being triggered by chilli pepper. (24)

It may be difficult to identify the responsible allergen when an individual reacts to curry, considering the various spices comprising that specific blend. A 22-year-old woman with urticaria, dyspnoea and asthma-like attacks after eating curried rice was shown to have immediate-type allergy caused by the spice contained in curry spice. A complicating factor was that she also experienced pollen-food allergy syndrome, with symptoms from melon and latex allergy. She was found to be skin-prick test-positive to (among others) cumin, fennel, dill, fenugreek, cayenne (chilli pepper), ginger, cardamom, garlic, garam masala, mustard seed, and coconut milk. (25)

Reactions may be severe. Occupation-related anaphylaxis after the intake of paprika, with concurrent rhinoconjunctivitis, was reported in a spice-and-condiment seller, The patient tolerated another Solanaceous vegetable in her diet. (26) Anaphylaxis may be food-dependent. In a study reporting on 7 cases of food-dependent exercise-induced anaphylaxis, the responsible foods were wheat (2 cases), maize, barley, shrimp, apple, paprika and mustard. (27)

Various components of sweet pepper may result in occupational disease. (28) Out of 472 sweet pepper greenhouse employees, work-related symptoms were reported in 53.8%. Sensitisation to the sweet pepper plant was found in 35.4%. Positive reactions to leaf, stem and/or juice, however, were associated in nearly 90% of cases with sensitisation to pollen, which appeared to be the most important allergen of the plant. Symptoms at work were found to be associated with an IgE-mediated allergy, due to the high and chronic exposure to sweet pepper pollen. (29)

Contact dermatitis, contact allergy and protein contact dermatitis have been reported frequently. (30, 31, 32) A group of 103 patients with suspected contact allergy to spices was tested with the European standard series. Among the spices, the highest numbers of reactions were found to nutmeg (28%), paprika (19%) and cloves (12%). (31) Occupational contact urticaria from paprika may also occur, (33) and protein contact dermatitis from paprika and curry has been reported in a cook. (32)

‘Hunan hand’ is a contact dermatitis resulting from the direct handling of chilli peppers containing capsaicin. (1)

In a French series of 202 labial food challenges performed in 142 children with suspected food allergy, 156 were positive. The most common foods provoking reactions were egg white (75 cases), peanut (60 cases), mustard (23 cases), cow's milk (13 cases), and cod (8 cases). One child was positive to chilli pepper. (34)

An Indian study of 24 children (aged 3 to 15 years) with documented deterioration in control of their perennial asthma – the purpose of which was to evaluate the possible effect of a specific elimination diet on symptoms – reported that specific IgE was raised to chilli in 3 (12.5%). (35)

Other reactions

Chronic occupational exposure to chilli peppers is associated with complaints of cough but does not of itself lead to decreased responsiveness of capsaicin-sensitive nerves when assessed by cough threshold. (36) Gustatory rhinitis has been attributed to chilli pepper, among other causes. In a survey of 571 individuals, 396 (69%) indicated at least 1 food resulted in gustatory rhinitis symptoms. Bread (6%) and hot chilli peppers (49%) represented the least and most common foods identified, respectively. (37)

Pungent-fruited peppers may cause painful irritation when used in excess, or after accidental contact with the eyes. Pepper spray containing the oleoresin of capsicum is used by law enforcement and the public as a form of nonlethal deterrent, but may result in corneal abrasions if in contact with the eyes. (38) The sap of the plant can cause the skin to blister.

Abdominal pain and gastric symptoms may occur. (39)

Erythema multiforme-like contact dermatitis has been reported. (40)

Effective protection against thrips (a common pest in sweet pepper horticulture) is possible without pesticides, through the use of the commercially available predatory mite Amblyzeius cucumeris. This mite is a new occupational allergen in horticulture, which may result in IgE-mediated allergy in exposed employees. In a group of sweet pepper horticultural workers, work-related symptoms were reported by 76.1%. Skin-specific IgE to this mite was found in 23% (109) of this group. Sensitisation to Tyrophagus putrescentiae was found in 62 employees, of whom 48 were also sensitised to A. cucumeris. (41)

Serum-specific IgE against paprika pollen, but not against Tomato pollen, was found in serum from 2 greenhouse workers who worked with paprika plants. A greenhouse worker who cultivated tomato plants had IgE against both tomato and paprika pollen. The authors conclude that the presence of IgE against paprika or tomato pollen is not restricted to workers in horticulture; IgE against these pollens may also be present in food-allergic patients who have serum IgE against paprika and/or tomato fruit. (42)

Laryngospasm associated with aspiration of a beverage spiked with Tabasco sauce has been reported. The authors postulate that this may have been as a result of mechanical irritation or chemical irritation of the patient's larynx. (43)

Last reviewed: June 2022