There are people who are lactose intolerant, and there are people who are allergic to dairy. There are people who are incredibly allergic to gluten, and there's people who just find it makes them bloated and uncomfortable. People often use the terms allergy and intolerance interchangably, but there's a few notable difference between them.

Allergies are an immune system reaction to a certain substance; they produce a range of symptoms like hives and swelling, which can be life-threatening (think hayfever at its greatest possible extreme). Intolerances are usually caused by a missing enzyme (can't digest the food properly), gut disorders (like irritable bowel), sensitivity to food additives (you're not allergic to the food itself, but have issues with something that's added in) or even stress.

The most basic tell-tale sign: if you can handle small amounts of the food, it's unlikely to be an allergy. Further, if you can handle a modified version (like lactose free milk or preserved fruit without sulfites), then it's unlikely to be an allergy.

The only way to be truly sure is to book in for an allergy test; your health practitioner will be able to determine whether it's an allergy or intolerance, and help you adjust your diet so you're not getting any unpleasant side effects.