While any food can theoretically cause a food allergy, citrus fruits are fairly low on the list.  However, allergy to citrus has been associated with adverse food reactions ranging from mouth itching to anaphylaxis.

The Genus “citrus” includes lemons, limes, oranges and grapefruits.  There is allergic cross reactivity between these citrus fruits, suggesting allergy to one, increases the risk of allergy to another in the group.  The seeds (which are abundant in protein) have increased allergenicity compared to the pulp or juice and share similar protein allergens.

Frequently, citrus allergy is associated with pollen allergy (especially grass) due to cross-reactive (shared) proteins. Also, citrus allergy shares a common Cit s 1 and Cit s 3 profilin isoform that is found in apples.

Lemons:

• A child with milk allergy had an anaphylactic reaction to lemon sorbet, but it turned out to be cross contaminated with milk.  He was not allergic to lemon.
• An adult with peanut allergy had co-sensitivity to citrus seeds and had anaphylaxis after using lemon soap containing crushed lemon seeds.
• A 17 year-old female with cashew allergy had been experiencing mouth itching and lip swelling with citrus for 10 years before she had anaphylaxis after eating lemon sorbet (lemon juice + lemon peel).  She was skin test positive to lemon and orange pulp as well as grapefruit peel.

Limes:

• Lime juice can cause dental erosion and decrease the anti-coagulant effect of Warfarin (Coumadin).  In rats, lime juice can partially block ovulation and may decrease fertility.    I was unable to find any reports on allergic reactions to lime juice.
• Oils in the rind of limes contain fucocoumarin which in some persons can be sensitizing and if contact is followed by sunlight exposure, a phototoxic reaction can occur which manifests as a red, itchy rash. This is called a phytophotodermatitis.  This citrus peel allergy from lemon, lime and oranges is triggered by limonene and lesser contact allergens geraniol and citral.  Beware bartenders: twisting lime into gin and tonics at the poolside bar may be hazardous to your skin!

Oranges (especially Mandarin):

• Anaphylaxis: A case in Greece identified a heat stable protein rather than the usual lipid transfer protein.
• In 2012, a case report published in Annals of Allergy described a 2 year-old boy who developed food-protein induced enterocolitis (repetitive vomiting, diarrhea, dehydration, lethargy) occurring 1-2 hours after drinking orange juice.  Skin and blood tests for allergies are negative in this type of reaction.
• Cashew and pistachio allergy are more common in children with orange seed allergy.  A child in Australia with cashew allergy chewed and swallowed the seeds from a mandarin orange and had a severe reaction within 1 hour.  He could drink the juice with no problems!

Grapefruit:

• Food-dependent exercise-induced anaphylaxis has been reported for orange and grapefruit.  This occurs when ingestion of the food and exercise occur within 2 hours.  Exercise alone or eating the food without exercise will not trigger the allergic reaction.

At Family Allergy Asthma & Sinus Care, we specialize in assessing and treating food allergic reactions.  If you suspect an allergy to citrus, call us.   If you have had a reaction to lime juice, you may the first!