BHA and BHT (E320, E321): Antioxidant Preservatives and the Skin

BHA (E320) and BHT (E321) are antioxidant preservatives that keep fatty foods from going rancid, and they turn up in cosmetics too. A plain-English UK guide to what they are, who reacts, and how to spot them on a label.

What they are

BHA (butylated hydroxyanisole, E320) and BHT (butylated hydroxytoluene, E321) are synthetic antioxidants. Their job is to stop the fats and oils in a product from oxidising, which is the chemical process that turns them rancid, stale and off-tasting. By slowing that reaction down, they extend the shelf life of fatty and oily foods.

They are two of the clearest examples of an ingredient that spans both your kitchen and your bathroom shelf. The same antioxidant protection that keeps a packet of crisps fresh also keeps the oils in a moisturiser or lipstick from spoiling, so BHA and BHT appear on food labels and cosmetic labels alike. That dual role matters for anyone with sensitive skin, because a trigger you meet in food you may also be meeting in the products you apply.

Which foods it’s in

BHA and BHT tend to be found wherever there is fat or oil to protect. In food, that commonly means crisps and savoury snacks, breakfast cereals, chewing gum, vegetable oils and cooking fats, margarine and spreads, instant mashed potato, dried and dehydrated products, and some processed and cured meats. They can also appear in flavourings and in the packaging of fatty foods.

Because they are used at very small levels, you will not taste them, and their presence has nothing to do with how “processed” a food looks. A plain-seeming cereal or a simple oil can contain them while something more obviously processed does not. The only reliable way to know is the label.

The UK rules

In the UK, food additives are regulated and must be declared on the ingredients list of any prepacked food. BHA and BHT are both permitted antioxidants, listed either by name or by their E-numbers, E320 for BHA and E321 for BHT. An E-number simply means the additive has passed a safety assessment and been approved for use, so seeing “E320” on a label is a sign the ingredient is a recognised, regulated additive rather than anything hidden.

Their function on a label is usually given as “antioxidant”, which tells you the role they play. Antioxidants and preservatives are not the same thing, though people often lump them together: a preservative fights microbes, while an antioxidant like BHA or BHT fights the oxidation of fats. Permitted levels are set in law and are specific to the type of food. For cosmetics, a separate set of rules applies, but the same two ingredient names appear, so a label-reading habit carries across.

The skin connection

BHA and BHT are actually better documented as contact allergens in cosmetics than as food triggers. Applied to the skin over time, they can cause allergic contact dermatitis, an itchy, red, sometimes scaly reaction, in people who have become sensitised to them. Some people also report contact urticaria, where hives appear where the product touched.

Eaten, they are an occasional trigger of hives (urticaria) in a sensitive minority, though this is far less common than the contact reactions. True, antibody-driven allergy to BHA or BHT is uncommon; most reported reactions are irritant or intolerance-type responses that depend on the individual and the dose. The confusing part is the overlap: because the same person can meet these chemicals in a crisp packet and in a lip balm, a flare can seem to come from nowhere until you realise both routes share the ingredient. If your skin reacts and you cannot pin it to a food, it is worth checking your skincare too.

How to spot it on a label

Scan the ingredients list for any of these names: BHA, BHT, butylated hydroxyanisole, butylated hydroxytoluene, E320 or E321. On food they will usually sit near the end of the list, often prefixed by the word “antioxidant” or “antioxidants”. On cosmetics the same chemical names appear, sometimes written as “BHA” or “BHT” in the INCI (International Nomenclature of Cosmetic Ingredients) list.

Watch for the acronym trap described above: cosmetic “BHA” as an exfoliant is salicylic acid, not butylated hydroxyanisole. If in doubt, the full chemical name settles it.

A balanced take on the evidence

It is worth being honest about the state of the science. BHA and BHT have been studied for decades, and there is ongoing scientific and regulatory debate about them at high doses in laboratory settings. That debate is separate from the practical question this site cares about, which is skin reactions in sensitive people at the everyday levels found in food and cosmetics.

For the general population, regulators consider both additives acceptable within permitted limits. The number of people who genuinely react to them on the skin is small, and much of that is contact allergy from cosmetics rather than anything eaten. So the honest position is neither alarm nor dismissal: these are not ingredients most people need to worry about, but if you are one of the minority whose skin reacts, the average result does not matter, your own pattern does.

What to do if you suspect it triggers your skin

Start by tracking, not cutting. Keep a short diary that records what you ate, the skincare and lip products you applied, and when your skin flared. Because BHA and BHT cross between food and cosmetics, noting both in the same place is the quickest way to spot an overlap that would otherwise look random.

If a pattern emerges, take it to a professional rather than acting alone. A GP can advise and refer, a registered dietitian can guide any dietary changes so your nutrition stays sound, and a dermatologist can patch test specifically for BHA and BHT if a contact allergy is suspected. Any elimination should be short, targeted and ideally supervised, never a broad, open-ended cull of foods. This is educational information to inform that conversation, not medical advice or a diagnosis.

Check products against your list

A free scanner like Yuka gives a packaged product a general health score, a useful broad read, though that verdict is the same for everyone rather than tuned to your skin. Fig is genuinely good if you are managing a defined eating pattern. To check a product against the specific things that make your skin react, a personal-list app like ClearaScan lets you save your triggers once and scan any product, food, medication or cosmetic, against your ingredient guard list, flagging only yours. Because BHA and BHT span food and skincare, scanning both against one list is exactly the case it is built for. Its Reaction Journal lets you tie a flare back to the product that caused it, a shared Care Circle lets family scan for you, and a Trusted Products list keeps what you have cleared. It is currently in early access. (Disclosure: our editor co-founded ClearaScan, and we are not paid to mention the others.)

Written and reviewed by the Sensitive Skin Lab editorial team.