Hops are a food which may result in allergy symptoms in sensitised individuals.

Hop Allergy Test: Allergen Exposure

Hops are in the same family as hemp, and originated in Eurasia. The hop plant is a perennial climbing plant which grows to a height of up to 6 metres. The term ‘hop’ commonly refers to the either the dried flower heads as a whole or the bitter, aromatic extract from the dried pine cone-like fruit of the plant.

Today, they are also cultivated in North and South America, Africa, Asia and Australia. Approximately 98% of hops produced worldwide are used in the production of beer.

Historically, hops were used in beer breweries as a preservative, before the invention of the pasteurisation process, however they are now an important component of the flavour profile of beer and so have been retained.

They are also used medicinally, mostly to treat sleep disturbances.

In some countries the young shoots, heads, leaves and roots of the plant are eaten as vegetables.

Extracts from the plant, including the oil, are used as flavouring in non-alcoholic beverages, frozen dairy desserts, candy, baked goods, puddings and tobacco.

The seeds contain gamma-linolenic acid, an essential fatty acid that is said to have many important functions in the human body and is rarely found in plant sources.

Hop Allergy Test: Allergen Description

No allergens present in hops have yet been characterised.

Hop Allergy Test: Potential Cross-Reactivity

An extensive cross-reactivity among the different individual members of the family could be expected, including with hemp (cannabis) and Japanese hops. Further investigations will be needed to evaluate the possibility of cross-reacting components.

Hop Allergy Test: Clinical Experience

Hops may uncommonly induce symptoms of food allergy in non-occupationally sensitised individuals. Occupational allergy may commonly be associated with exposure to Hops.

A patient who presented 4 times with systemic urticaria associated with arthralgia and fever has been reported; investigation confirmed allergy to hops.

Hops are also an uncommon cause of occupational asthma and anaphylaxis.

Skin contact with the plant causes dermatitis in susceptible people, and systemic and contact urticaria have been documented. Hops dermatitis has long been recognised. It is a mechanical dermatitis attributed to the rough hairs on the stem and secretions of the yellow glandular hairs.

Among 14 Polish farmers complaining of work-related skin symptoms, these were caused most often by hops (11%), followed by grain (5.6%), hay (5.5%) and straw (4.1%).

Anaphylaxis following exposure to Hops has been reported, and should be considered in individuals with “idiopathic” anaphylaxis.

The onset of occupational airborne dermatitis and hand dermatitis to hops has been documented. The patient had erythema of the face, neck and upper chest, oedema of the eyelids, and conjunctivitis, as well as acute dermatitis of the hands. Both fresh and dried hops precipitated the symptoms.

Occupational allergy to Hops has been reported. A chemist developed urticaria, rhinitis, conjunctivitis and asthma after 6 months’ work as a hop selector for a brewery.

Other reactions

Hop leaves contain lupin and rutin. Sometimes hops are treated with sulphur dioxide to improve the colour and prevent change of active substances.