Symptoms but no answers? Bloating, skin flare-ups, fatigue, brain fog or sinus issues can all be linked to food intolerances such as gluten, dairy, egg or yeast. This hub helps you map symptoms to likely causes and shows how to confirm your triggers.

From symptoms to clarity

Many people get labelled with “IBS” or “stress” when the underlying driver is diet-related. Intolerances create delayed reactions (30–72 hours), so the connection between a meal and symptoms is easy to miss. Use the grouped lists below to spot patterns, then test properly so you can take targeted action.

Digestive symptoms

  • Bloating, gas after meals
  • Abdominal cramps or discomfort
  • Diarrhoea, constipation or alternating bowel habits
  • Nausea or reflux

Common links: gluten, lactose/dairy, egg, yeast, food additives.

Skin symptoms

  • Eczema or dermatitis flare-ups
  • Acne or facial redness after certain meals
  • Itchy scalp, rashes or hives

Common links: dairy proteins (casein/whey), gluten, egg, additives.

Energy & fatigue symptoms

  • Post-meal energy crash
  • Persistent fatigue despite sleep
  • “Tired but wired” evenings

Common links: gluten, dairy, yeast/sugar sensitivity, inconsistent meal timing.

Mood & mental symptoms

  • Brain fog or slow thinking after meals
  • Low mood, irritability or anxiety spikes
  • Headaches or “pressure behind the eyes”

Common links: gut–brain disruption from gluten/dairy/egg sensitivities and additives.

Sinus & immune symptoms

  • Congestion, mucus after eating
  • Frequent throat clearing
  • Seasonal flare-ups that worsen with certain foods

Common links: dairy, wheat/gluten, histamine-rich foods, additives.

Joint & inflammation symptoms

  • Generalised aches or stiffness
  • Morning soreness that varies with diet
  • Exercise recovery feels unusually poor

Common links: gluten, dairy, processed foods and certain oils.

IBS or intolerance?

IBS is a collection of symptoms, not a single cause. If your digestion fluctuates with what you eat, start with intolerance investigation and basic gut support.

How to confirm your causes (without months of guessing)

Elimination diets can work, but they’re slow and easy to misinterpret. A broader screen checks multiple categories at once so you can act quickly.

Ultimate Intolerance Test — assesses 900+ items including gluten, dairy proteins, lactose, egg, yeast and additives. Home sample, fast digital results, practical plan.

Helpful reads from our blog

Credible sources: NHS pages on IBS and food allergy/intolerance; British Dietetic Association guidance.

Bottom line: Map your symptoms, test intelligently, and build a targeted plan so you can feel better—without cutting everything you love.

What are the most common food intolerances?

What’s the difference between a gluten intolerance and coeliac disease?