Allergies affect more than 20 million people in the UK1, with reactions ranging from mild discomfort to life-threatening situations. Awareness and education are crucial in preventing and managing allergic reactions. So, as we mark Allergy Awareness Week 2025, we are covering off some top ‘need-to-knows’ about allergies and the ingredients in your cosmetics and personal care products.
Not all reactions are allergies
The first need-to-know is whether the reaction is an allergy at all. Allergy is a term that is often misused to describe all kinds of adverse reactions, but actually there are two main types: irritant reactions and allergic reactions. While they may sound, and sometimes feel, similar, there is a big difference between being irritated by a substance and being allergic to it.
Irritant reactions are the most common adverse reaction and occur rapidly following use of a product. Redness of the skin, sometimes with an itch, is characteristic of an irritant effect. This clears up rapidly after ceasing to use the product that is causing the problem.
Allergic reactions involve the body's immune system. A person who becomes allergic to a substance will be sensitised to it for the rest of their life.
There are two main types of allergy
The next need-to-know is that there are two main types of allergy: immediate and delayed.
Immediate: this is an allergic reaction that occurs suddenly, generally a few minutes after exposure to the allergen (the substance that has caused the reaction). Common examples are hayfever triggered by pollen or allergic asthma triggered by animal hair.
Delayed: this type of allergic reaction does not show until some time, usually 24 to 72 hours, after contact with the allergen. An example is 'allergic delayed contact dermatitis' triggered by skin contact with the allergen.
Almost anything can cause an allergic reaction
It’s important to know that almost any substance, whether natural or man-made, has the potential to cause an allergic reaction. This is because our bodies are all different and allergies occur when our bodies react to a substance. Take peanuts, for instance, most people enjoy them without ever experiencing issues, while some can have very severe reactions to them. It’s the same with pollen - some of us will suffer from hayfever, while most people will never have to consider the pollen count.
Some ingredients in cosmetics may cause allergies
Substances known to cause widespread allergic reactions are not used in cosmetics but, because our bodies all behave differently, we might find we are allergic to substances in our cosmetics and toiletries. It is important to always check the ingredients list of the cosmetic product you intend to buy or use to make sure it does not contain any ingredients to which you are allergic. Some of the ingredients in cosmetics and personal care products that can more commonly cause allergic reactions include:
Preservatives: these are safe ingredients which are essential for keeping our products bug-free, so avoiding them completely just isn’t necessary or possible. However, some preservatives can cause allergic reactions in some individuals. There is a small pool of effective preservatives that are allowed to be used in cosmetic products, which means that, if you experience any issues with a certain ingredient, you can be confident about which one to avoid in the future, by checking the ingredients list. Find out more about preservatives in cosmetics and personal care products here.
PPD in hair dyes: the ingredient para-phenylenediamine (PPD) is used in permanent hair dyes because it’s the best way to achieve permanent hair colour and cover grey hair. While the number of reactions to PPD in hair dye are very low, it’s important to follow the instructions on pack. This includes always carrying out an allergy alert test when instructed (more on this below).
Fragrance (Parfum): fragrances are included in all kinds of products and though rare, reactions to them can sometimes occur. If you’re allergic to certain fragrance ingredients you should avoid all fragrance, which is shown on the list of ingredients by the word "parfum", unless you’ve checked that the specific fragrance ingredient to which you’re allergic is not included in the product. Helpfully, a large number of fragrance ingredients known to cause a higher incidence of allergy will be listed individually on the pack to help you make an informed choice. Find out more about fragrance allergies and fragrance-free cosmetic products here.
Ways to stay allergy aware
Since there is the possibility for anyone to be allergic to almost anything, including the ingredients in our favourite cosmetics and personal care products, it’s important to know how to stay allergy aware. Here are some of the steps you can take to protect yourself and your loved ones.
Always look at the label: Ingredient labelling can help you to identify products that contain ingredients to which you know you’re allergic. By law, all cosmetic products sold in the UK must display a complete ingredients list and must use the International Nomenclature of Cosmetic Ingredients, known as INCI. You can find the INCI names for cosmetic ingredients that are more frequently associated with allergies here.
Allergy alert test: We’ve touched on this already but it’s so important. If you’re planning to dye your hair at home or in the salon, always carry out an allergy alert test (sometimes referred to as a ‘patch test’) first when this is instructed on the product. This allows you to test a small amount of the product you plan to use on your skin to check if you’re likely to have an allergic reaction to it. Find out more about allergy alert tests here.
Avoid ‘Black henna’ tattoos: While the ingredient para-phenylenediamine (PPD) is used safely in permanent hair dyes it is sometimes used illegally in so-called ‘black henna’ temporary tattoos. When PPD is applied directly to the skin in a tattoo it can leave you with a swollen, sore, red ‘burn’. It can also sensitise you to PPD, making your skin more susceptible to future reactions when you use other safe products containing PPD, including hair dyes. Download our factsheet on ‘black henna’ temporary tattoos here.
Don’t use professional-only nail products at home: UV Gel and L&P Nail Systems can cause allergic reactions and skin inflammation in some people, if not applied correctly. These issues aren’t just confined to your fingertips, problems can occur anywhere the nail gel comes into contact with your skin - even on the face. These sorts of reactions can cause skin damage and lifelong side-effects. Never use nail products or equipment labelled as ‘professional-use only’ at home - it’s not worth the risk. Find out more about allergies to artificial nails here.
Get expert advice and support: While most reactions turn out to be irritations, if you are experiencing serious symptoms always contact a medical professional for advice. You should also contact the manufacturer of your product (careline or helpline numbers are provided on the pack) so that they are aware that someone has experienced a reaction to their product.
Explore more information about allergies and how to keep yourself allergy savvy this Allergy Awareness Week:
- Find more general facts about allergies and how they work here
- Explore the issue of hair dye allergy in more detail here
- Download a dedicated factsheet on artificial nails and allergy here
- Download our guide to what to do if you experience an unwanted reaction here
1All Party Parliamentary Group for Allergy and the National Allergy Strategy Group Report: ‘Meeting the challenges of the National Allergy Crisis’ 2021
