Yeast allergy
Yeast allergy or sensitivity.
About yeast allergy
Yeast is a microscopic fungus used to make bread rise and to ferment beer and wine, and it is also present as brewer's and baker's yeast and in some spreads and stock cubes. True IgE-mediated allergy to yeast, in which the immune system makes antibodies to yeast proteins, is uncommon; many people who believe they react to yeast are actually responding to other ingredients, to fermentation by-products or to a non-allergic intolerance. Genuine allergy does occur, however, particularly to brewer's yeast.
Symptoms of immediate allergy usually appear within minutes to two hours and may include an itchy mouth, hives, swelling, stomach upset, wheeze and, rarely, anaphylaxis. Some people report bloating, headaches or other vague symptoms after yeast-containing foods that are better explained by intolerance than by allergy. Because baker's and brewer's yeast are related, someone allergic to one may react to the other, and there can be overlap with sensitivity to moulds in certain individuals.
Diagnosis relies on the history supported by skin-prick or specific-IgE testing, and sometimes a supervised challenge to separate allergy from intolerance. Management means avoiding yeast in bread, fermented drinks, spreads and stocks where it genuinely causes symptoms, with care to keep the diet varied. Most reactions are mild, but any throat swelling or breathing difficulty is a medical emergency requiring 999.
Common triggers
- Yeast and products containing it
Symptoms
- Itching or tingling in the mouth
- Hives, itching or eczema
- Swelling of the lips, face, tongue or throat
- Stomach cramps, nausea, vomiting or diarrhoea
- Wheezing or trouble breathing
- In severe cases, anaphylaxis
Avoidance & management
- Read ingredient labels every time
- Ask about ingredients and cross-contamination when eating out
- Keep the food out of shared cooking areas
- Carry prescribed antihistamines or an adrenaline auto-injector
- Seek emergency help for any severe reaction
Sources & references
Allergy safety: what everyone should know
Mild-to-moderate reaction signs
- Itching, hives or a raised rash
- Swelling of lips, face or eyes
- Tingling mouth, sneezing, runny nose
- Stomach pain, nausea or vomiting
Anaphylaxis — call 999 (UK) or 112 (EU) immediately
- Difficult or noisy breathing, wheeze, persistent cough
- Swelling of the tongue or tightness in the throat
- Dizziness, collapse, pale and floppy (young children)
- Use an adrenaline auto-injector (e.g. EpiPen) at once if prescribed, then call an ambulance even if symptoms improve
Allergy or intolerance? A true allergy involves the immune system and can escalate quickly; an intolerance (e.g. lactose intolerance) is unpleasant but not life-threatening. The symptoms overlap, so self-diagnosis is unreliable.
Getting tested: home-testing kits based on IgG are not diagnostically valid. If you suspect an allergy, ask a GP for referral to an allergy clinic for skin-prick or specific-IgE testing and a supervised food challenge where appropriate.