A nut allergy is an immune reaction that can be life-threatening: it usually starts within minutes and can cause swelling, hives, wheezing or collapse. A nut intolerance does not involve that kind of immune reaction; it causes slower symptoms, mostly in the gut, that are uncomfortable but not dangerous.
If you have ever had swelling of your lips, mouth or throat, hives, wheezing or difficulty breathing after eating nuts, treat it as a possible allergy. Avoid nuts and see your GP, who can refer you for allergy assessment. Intolerance testing is not a substitute for allergy testing.
If your symptoms are digestive, appear hours later and you have never had an allergic-type reaction, this guide will help you work out what is going on.
What are the signs of a serious reaction to nuts?
The NHS lists these signs of anaphylaxis, a severe allergic reaction:
- Swelling of the throat and tongue
- Difficulty breathing or breathing very fast
- Difficulty swallowing, tightness in the throat or a hoarse voice
- Feeling faint, dizzy or fainting
- Skin that feels cold to the touch
Hives, swollen lips or eyes, and vomiting can come first. If someone has these symptoms, use an adrenaline auto-injector if they have one, call 999 and say you think it is anaphylaxis, and help them lie down with their legs raised.
How can you tell a nut allergy from a nut intolerance?
| Nut allergy | Nut intolerance | |
|---|---|---|
| What is happening | The immune system reacts to proteins in the nut | A digestive response, without that immune reaction |
| When symptoms start | Usually within minutes | Usually a few hours later |
| How much it takes | Tiny traces can be enough | Usually linked to how much you eat |
| Typical symptoms | Swelling, hives, itching, wheezing, vomiting, collapse | Bloating, wind, stomach ache, loose stools, a heavy feeling |
| How serious | Can be life-threatening | Uncomfortable, not dangerous |
| How it is assessed | GP and specialist: skin-prick tests, blood tests and supervised food challenges | Food diary, elimination and careful reintroduction |
The NHS guide to food allergy explains how allergy assessment works. For the wider picture across all foods, read our guide to food intolerance versus allergy.
Are peanuts nuts?
Not botanically. Peanuts are legumes, related to peas and beans, although we eat them like nuts. UK food law treats peanuts and tree nuts as two separate allergens among the 14 that must be declared. Tree nuts include almonds, hazelnuts, walnuts, Brazil nuts, cashews, pecans, pistachios and macadamia nuts.
Being allergic to peanuts does not automatically mean being allergic to tree nuts, or the other way round, but some people react to both. If you have a diagnosed allergy, your allergy team will tell you which nuts are safe.
Why can nuts upset your stomach without an allergy?
- Fat: nuts are rich in fat, so a large handful or a few spoonfuls of nut butter can leave you feeling heavy, queasy or with loose stools.
- Fibre: a sudden increase in nuts, seeds and wholegrains can cause wind and bloating while your gut adjusts.
- FODMAPs: some nuts, notably cashews and pistachios, are high in fermentable carbohydrates. Our guide to FODMAPs and bloating explains why these can cause wind.
- Hidden amounts: nut milks, nut flours, granola and energy balls make it easy to eat far more nuts than you realise.
- Coatings and seasonings: dry roasted and flavoured nuts can contain wheat, spices and other ingredients that may be the real trigger.
If almonds in particular seem to be the problem, our guide to almond intolerance covers the signs and alternatives.
Why does my mouth itch after hazelnuts or almonds?
Some people with hay fever, especially to birch pollen, get an itchy or tingly mouth or lips after eating raw hazelnuts, almonds or certain fruits. This is known as pollen food syndrome, sometimes called oral allergy syndrome. It is an allergy-type reaction that is usually mild and limited to the mouth, but because nut reactions can occasionally be more serious, it should be checked by a GP rather than managed on your own.
How do you manage a nut intolerance safely?
This approach is only for people who have never had allergic-type symptoms with nuts.
- Keep a diary. Note the type of nut, how much, whether raw, roasted or as a butter or milk, and when symptoms started.
- Try a smaller portion first. Many people find a small handful is fine where a large one is not.
- Take a short break. If smaller portions do not help, cut out nuts and nut products for two to four weeks.
- Reintroduce one type at a time. Start with a small amount of a single nut and wait two to three days before trying another.
- Read labels. Nuts turn up in pesto, sauces, curries, cereal bars, baking and many plant-based products.
For a general introduction to working out food triggers, see our beginner’s guide to food sensitivities.
When to speak to a GP
- You have had any allergic-type symptoms after nuts, even mild ones that passed quickly.
- Your mouth or lips itch or tingle when you eat nuts.
- A child may have reacted to nuts. Speak to a GP rather than testing at home; our guide to food intolerance in children covers what parents can safely do.
- Digestive symptoms continue after you have cut nuts out.
Where hair sample testing fits
If allergy has been ruled out and you want to understand slow, digestive symptoms, testing can give you a starting point for your food diary and help you decide what to try removing first. Nuts are often only part of the picture, and testing looks across many foods at once.
The Core Intolerance Test tests 500 food items, including peanuts, dry roasted peanuts, almond, Brazil nut, cashew nut, hazelnuts, macadamia nuts, pecan nuts, pine nut, walnuts, chestnut and coconut. Pistachios are not a separate item on our list.
A low response on your report never means a nut is safe for someone who might be allergic. Never use a result to decide to eat a nut that has caused allergic-type symptoms.
Your report groups items into high, medium and low response and includes a 6–8 week elimination plan and a printable food diary. It arrives by email within 3–5 working days of your sample arriving, or 48 working hours with priority.
Frequently asked questions
Can you be intolerant to nuts without being allergic?
Yes. Some people get bloating, wind, stomach ache or loose stools after nuts without any immune reaction. These symptoms are usually slower to appear and linked to how much you eat. Anyone who has had swelling, hives or breathing difficulty after nuts should be assessed for allergy.
How quickly does a nut allergy reaction start?
Allergic reactions to nuts usually start within minutes of eating them. Symptoms that build slowly over several hours and stay in the gut are more typical of intolerance. If you are unsure, treat a reaction as a possible allergy and speak to a GP.
Can a nut allergy develop in adulthood?
Yes, nut allergies can appear at any age, including in adults who have eaten nuts for years. New symptoms such as lip swelling, hives or an itchy mouth after nuts should be checked by a GP.
Is coconut a tree nut?
Coconut is not listed among the tree nuts that must be declared on UK food labels. If you have a diagnosed nut allergy, ask your allergy team whether coconut is safe for you.
This guide is general wellness information, not medical advice. Our test uses bioresonance, a complementary (CAM) method; it does not diagnose allergies, coeliac disease or any medical condition. Speak to a GP if you have severe or ongoing symptoms.
