For individuals with a tree nut and/or peanut allergy under the care of an allergy specialist, advice may vary as to whether you need to avoid all nuts or only specific nuts. This decision can be a complex clinical one based on the age of the patient, history of past reactions, co-existing medical conditions and results of oral food challenges. 
Seek advice from your doctor or allergy specialist.

If a person is allergic to one unique protein present in one food only (such as peanut or egg) then an allergic reaction can only occur if they eat that one particular food. However, some individuals may be allergic to more than one protein (cross-reactive proteins) in more than one food and so may be allergic to several foods. Cross reactivity occurs in people allergic to similar proteins present in, for example, cashews and pistachio nuts.  In other words, most people allergic to cashews are also allergic to pistachios. However, it’s impossible to predict if someone will be allergic to more than one protein without allergy testing for a particular food. Reliable diagnosis of food allergy is therefore important.

Once diagnosis is confirmed, the only treatment at this stage is total avoidance of the allergen.

Peanuts are legumes, like peas, lentils and chickpeas. The proteins in peanut are very different to those in tree nuts (such as almonds, Brazil nuts, cashews, hazelnut, macadamia nuts, pecans, pistachios or walnuts). Therefore, someone allergic to peanut is not automatically going to be allergic to tree nuts.

For those who can safely eat certain types of nuts, it’s important to ensure that there is no cross contact with other nuts. If cross contact can be completely avoided, such as where nuts are in their shell, or where the grower can guarantee the nut has not come into contact with any other nut, they are deemed safe to consume.