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). Capsaicin present in Paprika may be implicated in the bronchoconstriction of airways (2) and has also been found to increase permeability in a model of human intestinal epithelium (3).

Probably native of the tropics, Sweet Peppers are grown mainly in China; the Dominican Republic, Haiti, Hawaii, Iraq, Japan, Malaya, Mexico, Spain, Hungary and Turkey. Most commercial Paprika comes from Spain, South America, California and Hungary, with the Hungarian variety considered by many to be superior. It is used as a spice in many cuisines worldwide.

C. annuum (Sweet Pepper), as opposed to C. frutescens (Chili or Cayenne Pepper), is used mainly as a vegetable. It usually has a mild, sweet flavor, and is eaten raw or cooked. It also serves as a source of condiments and spices, especially in dishes of Latin America and the East.

Not known in the wild, Sweet Peppers are grown in cultivated beds. The flavour can range from mild to pungent and hot, the color from green to deep blood-red to pink. Peppers are often found as a vegetable in stews and salads. Jalapeno Pepper is a variety of this species, and is used both as a condiment and in the making of green Tabasco sauce; another very hot red variety goes into red Tabasco sauce. Special red varieties are dried to make Paprika powder, which is relatively mild compared to Chili powder. Paprika is used as a seasoning and garnish for a plethora of savoury dishes, and sometimes serves as a food colouring. Young leaves of the plant are steamed as a potherb or added to soups and stews. The flowers can be eaten raw or cooked.

Peppers are a good source of dietary antioxidants, apart from 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 fruit of the Pepper 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 has been used as a riot control agent.

Allergen description

The following allergens have been fully characterised:

• Cap a 1, a thaumatin-like protein (4)  
• Cap a 1w, an osmotin-like protein; homolog: pathogenesis-related protein PR5

Also profilin and a Bet v 1 homologue have been detected in Sweet Pepper (5). Examination of a variety of horticultural strains of Sweet Peppers demonstrated the presence of profilin in all and Bet v 1homologues in 50%, suggesting that Sweet Peppers have to be considered potentially dangerous for Bet v 1- 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 (6-7). The P23 allergen appears to be a 23 kDa allergen. Other uncharacterised allergens detected were of a higher molecular weight (7).

A beta-1,4-glucanase, a cell wall-associated enzyme believed to function in fruit ripening, has been isolated from Sweet Pepper (8). This enzyme in other plants has been shown to have allergenic activity, but its allergenic relevance in Sweet Pepper has not yet been determined.

Potential Cross Reactivity

An extensive cross-reactivity among the different individual species of the genus could be expected (9). Antigenically crossreactive material from tobacco leaf was demonstrated in Eggplants, Sweet pepper, Potato, and Tomato; all members of the family Solanaceae (10).

Cross-reactivity to other plants containing the panallergens profilin and Bet v 1 homologues can be expected to occur frequently. Patients with allergy to Sweet Pepper and associated pollinosis show a high frequency of IgE reactivity to profilin (11-12). Although some strains of Sweet Pepper contain a homologue of the osmotin-like protein P23 from Tomatoes, which in vitro is responsible for substantial IgE binding (6, 7), the clinical relevance of this allergen has yet to be determined.

A high frequency of sensitisation to Sweet Pepper has been frequently reported in Latex-allergic patients (11, 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 prohevein, and a beta-1,3-glucanase (11, 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 (6, 18-22). Urticaria as a result of contact with Paprika has been documented (23). Specific IgE antibodies to Sweet Pepper have been measured by Phadebas RAST (24).

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 were 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).

The complexity of the relationship of allergens, the degree of individual variability, and the severity of the reactions are illustrated by a spice-and-condiment seller who experienced occupational-related anaphylaxis and concurrent rhinoconjunctivits caused by intake of Sweet Pepper. The patient tolerated other Solanaceae products, and attempts to inhibit IgE binding to Capsicum by other Solanaceae members failed (25).

In a study reporting on 7 cases of food-dependant exercise-induced anaphylaxis, the responsible foods were Wheat (2 cases), Maize, Barley, Shrimp, Apple, Paprika and Mustard (26).

Various components of Sweet Pepper may result in occupational disease (27).

Among 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% 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 (28).

Contact dermatitis, contact allergy and protein contact dermatitis have been frequently reported (29-31). 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%) (30). This study suggested that IgE-mediated immediate-type responses are directed against different antigens from those eliciting delayed responses.

Occupational contact urticaria from Paprika may also occur (32), and protein contact dermatitis from Paprika and curry has been reported in a cook with no history of atopy. He was found to have elevated total IgE and a high level of specific IgE to Sweet Pepper as tested by the Pharmacia CAP System. The results correlated well with a skin prick test (31).

Other reactions

Pungent-fruited Peppers may cause painful irritation when used in excess, or after accidental contact with the eyes. Pepper spray containing oleoresin 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 (33). The sap of the plant can cause the skin to blister.

Erythema multiforme-like contact dermatitis has been reported (34).

Protection against thrips, a common pest in Sweet Pepper horticulture, is effectively possible without pesticides through 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 (35).

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 can also be present in food-allergic patients who have serum IgE against Paprika and/or Tomato fruit (36). 

Last reviewed: June 2022.