You can be allergic to grapefruit but not oranges.
Although both oranges and grapefruit are citrus fruits, they also do contain different proteins which can trigger allergic reactions in some people.
Some people may be allergic to both grapefruit and oranges, although it's also possible for some people to be allergic to just grapefruit and not oranges or some people may also be allergic to just oranges and not grapefruit.
Allergies to grapefruit are often caused by the protein called "profilin," which is found in the seeds and pulp of the grapefruit.
And oranges, contain a different protein that is called "citric acid," which is also less likely to cause allergic reactions.
An allergic reaction to grapefruit can cause skin reactions such as eczema, hives and itching as well as gastrointestinal issues like nausea, abdominal pain, diarrhea and or vomiting.
An allergic reaction to grapefruit can also cause respiratory symptoms and problems like wheezing, coughing, sneezing and or congestion.
And oral allergy syndrome can also occur due to an allergic reaction from grapefruit which causes itching or swelling of your lips, tongue or throat.