The likely culprit is nickel, not a peanut allergy. Peanuts are legumes, and legumes are among the higher-nickel foods, so peanut butter can flare systemic nickel allergy with symptoms like eczema, itching or gut upset. That is a completely different mechanism from an IgE peanut allergy, which is why you can react to the nickel while testing negative for a peanut allergy.

No. A peanut allergy is an IgE immune reaction that can cause anaphylaxis and requires strict avoidance. A peanut intolerance is a reaction to the food chemistry, such as the oxalates, nickel or salicylates in peanuts, and it causes discomfort rather than a life-threatening response. If you have any doubt about which one you have, get tested.

Peanut is the defining ingredient of Indonesian and Malaysian satay sauce, so assume yes. A small number of kitchens make nut-free versions with seed or soy bases, and some Western recipes substitute other nut butters, but neither is common enough to rely on. With a diagnosed peanut allergy the safe approach is to confirm with the kitchen every time, ask about shared grills, tongs and fryers, and treat an unlabelled satay-style dressing as peanut until proven otherwise.

Peanuts are high in oxalates, moderately high in nickel and salicylates, and high in lectins. Any of these can cause symptoms without an allergy being involved, so people with systemic nickel allergy, salicylate sensitivity or a tendency to kidney stones often feel worse after peanuts even with a clear allergy test.

It is moderate. Peanuts and peanut butter carry a meaningful oxalate load, so if you are a kidney-stone former or following a low-oxalate plan, a thick spread counts. It is not as extreme as spinach or almonds, but a daily habit adds up.