Food Intolerance Symptoms Checklist

Food Intolerance vs Food Allergy: Know the Difference

Before diving into symptoms, it is important to understand the distinction. The NHS defines these as two very different conditions:

Digestive Symptoms Checklist

Digestive symptoms are the most commonly reported signs of food intolerance. They result from the body's inability to properly break down or process certain food components.

• Bloating: Abdominal distension and feeling of fullness, often worse after meals. One of the most frequently reported symptoms, particularly with lactose and FODMAP intolerances
• Excess gas (flatulence): Produced when undigested food ferments in the large intestine. Common with lactose intolerance and FODMAP sensitivity
• Abdominal pain or cramping: Can range from mild discomfort to sharp cramps. May be localised or generalised across the abdomen
• Diarrhoea: Loose or watery stools, often occurring 2-12 hours after eating trigger foods. Common with lactose intolerance and fructose malabsorption
• Constipation: Less commonly associated with intolerances but can occur, particularly with gluten sensitivity in some people
• Nausea: Feeling of queasiness after eating, sometimes with or without actual vomiting
• Acid reflux or heartburn: A burning sensation in the chest or throat. Certain foods (fatty foods, caffeine, alcohol, citrus) are well-known triggers
• Urgency: A sudden, pressing need to use the toilet after eating
• Stomach gurgling: Audible rumbling or gurgling sounds (borborygmi) after eating, caused by gas and fluid movement

Skin Symptoms Checklist

The connection between food and skin is well-established in medical literature, though it is often underappreciated. Skin symptoms from food intolerance tend to be delayed, appearing 6-48 hours after eating.

• Eczema flare-ups: Worsening of existing eczema (atopic dermatitis) after eating certain foods. The NHS notes that food can be a trigger for eczema, particularly in children
• Hives (urticaria): Raised, itchy welts on the skin. Can be allergy-related (immediate) or intolerance-related (delayed)
• Itchy skin: Generalised itching without a visible rash, sometimes described as "prickly" or "crawling" sensations
• Flushing: Reddening of the face, neck, or chest, commonly associated with histamine intolerance, alcohol, or spicy foods
• Acne flare-ups: Some people report worsening acne after consuming dairy or high-glycaemic foods, though research is still evolving
• Dark circles under eyes: Sometimes called "allergic shiners," these can be associated with chronic food sensitivities, though many other factors contribute
• Dry or flaky skin: Persistent dry patches that do not respond well to moisturisers may be connected to underlying food sensitivities in some cases

Neurological Symptoms Checklist

These symptoms are sometimes the hardest to connect to food because they feel so separate from what you have eaten. Yet they are commonly reported by people with confirmed food intolerances.

• Headaches and migraines: Certain foods are well-established migraine triggers, including aged cheese, chocolate, red wine, processed meats (nitrates), MSG, and aspartame. Histamine-rich foods can also cause headaches
• Brain fog: Difficulty concentrating, feeling mentally "sluggish," or struggling to find words. Often reported 2-6 hours after eating trigger foods
• Fatigue: Persistent tiredness that goes beyond normal post-meal drowsiness. Some people describe feeling "wiped out" after eating certain foods
• Dizziness: Feeling lightheaded or unsteady, sometimes associated with blood sugar fluctuations triggered by food sensitivity
• Irritability and mood changes: Some people report feeling unusually irritable, anxious, or low after consuming certain foods. The gut-brain connection is an active area of research
• Poor sleep: Difficulty falling or staying asleep, particularly if trigger foods are eaten in the evening

Respiratory and Other Symptoms

Less commonly associated with food intolerance, but worth noting:

• Nasal congestion: A stuffy or runny nose after eating. Sometimes called "gustatory rhinitis" when triggered by spicy or hot foods, though dairy and other intolerances can also cause chronic congestion
• Sinus pressure: Feeling of fullness or pressure around the nose, cheeks, and forehead
• Post-nasal drip: Mucus draining down the back of the throat, sometimes causing a persistent cough
• Joint pain and stiffness: Some people report worsening joint symptoms after eating certain foods, though the evidence is mixed and other causes should be investigated first
• Mouth ulcers: Recurring mouth ulcers can sometimes be linked to food sensitivities, particularly to certain fruits, nuts, and chocolate
• Unexplained weight fluctuations: Rapid weight changes (often fluid-related) that correlate with eating certain foods

Common Trigger Foods in the UK

While any food can potentially cause an intolerance, some are far more common than others. Here are the most frequently reported triggers in the UK:

Source: NHS — Food Intolerance; Allergy UK; British Dietetic Association

How Tracking Helps You Identify Your Triggers

The challenge with food intolerance symptoms is that they are non-specific — bloating can be caused by dozens of different foods (or by stress, hormones, or illness). Tracking transforms vague suspicions into concrete evidence.

What consistent tracking reveals

• Timing patterns: You may discover that your headaches consistently appear 4-6 hours after eating aged cheese but not after fresh cheese — pointing to histamine as the issue
• Dose thresholds: Perhaps a small amount of milk in tea is fine, but a full latte triggers bloating. Many intolerances are dose-dependent
• Cumulative effects: Some people tolerate a trigger food once but react when they eat it multiple times in a day or over several days
• Confounding factors: Tracking stress, sleep, and exercise alongside food helps you distinguish between food-triggered symptoms and those caused by lifestyle factors

Most healthcare professionals recommend tracking for at least 2-4 weeks before attempting to draw conclusions. This gives you enough data to see genuine patterns rather than coincidences.

When to See Your Doctor

While food intolerances are not dangerous, some symptoms warrant medical attention to rule out other conditions. See your GP if:

• Symptoms are persistent and affecting your daily life or mental health
• You are losing weight unintentionally
• You notice blood in your stool
• Symptoms are getting progressively worse over time
• You have a family history of coeliac disease, inflammatory bowel disease, or bowel cancer
• You are considering removing major food groups from your diet (a dietitian should supervise this)
• Over-the-counter remedies are not helping
• You experience symptoms that could indicate allergy (swelling, breathing difficulty, rapid reactions)

Next Steps: From Checklist to Action

If you have recognised several symptoms on this checklist, here is a sensible action plan:

• Step 1: Start a detailed food diary. Record everything you eat and drink, along with any symptoms, their severity, and timing. An app like NutraSafe makes this easier by timestamping entries and calculating nutritional content automatically
• Step 2: Track consistently for 2-4 weeks without changing your diet. You need baseline data before making changes
• Step 3: Review your diary for patterns. Look for foods or ingredients that consistently precede your symptoms
• Step 4: Take your food diary to your GP. This data is genuinely valuable — it helps your doctor decide on next steps, whether that is a referral to a dietitian, testing for conditions like coeliac disease, or a supervised elimination diet
• Step 5: If advised, work with a registered dietitian on an elimination and reintroduction plan. This is the gold standard approach and ensures you maintain nutritional balance

The goal is not to fear food, but to understand your body better. Most people with food intolerances find that once they identify their specific triggers, they can manage their symptoms effectively while still enjoying a varied, enjoyable diet.

Frequently Asked Questions

Related Resources

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