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What is acne?

29 Nov 2022

It’s the most common skin condition in teenagers, but acne affects adults, too. Get the lowdown on what causes this inflammatory skin condition, and how to prevent it

Written by Christina Quaine on February 15, 2019 Reviewed by Dr Nicole Chiang on February 27, 2019

It’s safe to say that if you’re plagued by pimples, you’re not alone – around 80% of British teens and young adults aged 11 to 30 have acne, according to the NHS.1 But the spots and soreness aren’t just a teen thing: while some adults continue getting acne in their 30s, 40s and 50s, adult-onset acne is becoming a growing problem, and now affects 20% of women.2,3

But is there anything you can do to prevent acne? And why does it happen in the first place? Find out in this guide.

So, what exactly is acne?

Acne is an inflammatory skin condition that happens when your hair follicles become blocked with dead skin cells and excessive sebum – the protective oil produced by your skin’s sebaceous glands, which sit next to the hair follicles.4 Excessive sebum causes overgrowth of a type of bacteria called Propionibacterium acnes. This bacteria normally lives on our skin: however, an overgrowth leads to spots and inflammation on your face, chest, upper back and shoulders. Your skin might feel hot, painful and tender to touch, too.5

Why does it happen?

From puberty, the hormone testosterone is released into the sebaceous glands in both sexes, and this triggers sebum production.

But in people who are prone to acne, their sebaceous glands are particularly sensitive to testosterone – and your sebum production can go into overdrive, leading to oily skin. If, at the same time, the dead skin cells lining your pores don’t shed properly, your hair follicles can become clogged, and bacteria can multiply – leading to acne symptoms.6

It’s still not fully understood why some people get acne while others have clear skin, but the following have been shown to be linked:


Yes, acne can run in families. In a 2018 study from King’s College, London, researchers reported that your genes even determine how your hair follicles develop – and in people prone to acne, the structure of their hair follicles makes them more likely to be colonised by bacteria.7

Foods with a high glycaemic index

Consuming high glycaemic foods and drinks that raise your blood sugar quickly, such as white bread, sugary drinks and biscuits, can also increase your risk of acne. A 2016 review from Poland’s Medical University of Warsaw found that these foods increase levels of insulin – the hormone that regulates your cells’ take-up of glucose – stimulating oil production in the sebaceous glands, and ramping up the acne risk.8


It’s also been shown that consuming cow’s milk boosts your risk of having acne. A 2018 study in Clinical Nutrition reported a link between cow’s milk – whether skimmed, semi-skimmed or whole milk – and the development of acne, although no such link was found for yoghurt or cheese.9 It’s thought that milk contains amino acids that increase your susceptibility to acne.10

Who gets acne?

Teenagers, mainly – it’s the most common skin condition for teens, affecting more boys than girls overall.11 But when it comes to adult-onset acne, women are more likely to experience it – more than 80% of adult acne cases are women, thought to be because of the hormonal fluctuations we go through during periods, pregnancy or if you have polycystic ovary syndrome.12

What to do if you have acne

To help manage the condition:

  • take time to relax – a 2017 study in Clinical, Cosmetic and Investigational Dermatology found that stress can trigger or worsen acne break-outs13
  • try not to pick or squeeze your spots – this can cause scarring
  • always remove make-up and clean your skin before bed using a gentle cleanser – but don’t be tempted to scrub hard: acne is never down to poor hygiene14

  • choose a moisturiser containing aloe vera, witch hazel, green tea or ginkgo biloba. A 2014 study in The Journal of Clinical and Aesthetic Dermatology found that these ingredients have an anti-inflammatory action that can help soothe acne-prone skin15
  • try jojoba oil – a German study in 2012 reported a 54% reduction in acne spots after six weeks of applying a clay mask containing jojoba oil16

Do you need to see your GP about acne?

A pharmacist can help with mild acne. But if your symptoms are moderate or severe – for example large, painful nodules or cysts – it is best to speak to your GP or a dermatologist.18 Shop Vitamins & Supplements Advice is for information only and should not replace medical care. Please check with your GP before trying any remedies.


1. NHS. Overview: Acne 2. American Academy of Dermatology Association. Adult acne 3. Luisa Dillner. The Guardian. Have I got adult-onset acne – and do I need treatment? 4. Mayo Clinic. Acne

5. As above

6. British Association of Dermatologists. Patient Information Leaflet: Acne 7. Petridis C, et al. Genome-wide meta-analysis implicates mediators of hair follicle development and morphogenesis in risk for severe acne 8. Kucharska A, Szmurlo A, Sinska B. Significance of diet in treated and untreated acne vulgaris 9. Aghasi M, et al. Dairy intake and acne development: A meta-analysis of observational studies 10. Juhl CR, et al. Dairy Intake and Acne Vulgaris: A Systematic Review and Meta-Analysis of 78,529 Children, Adolescents and Young Adults 11. Institute for Quality and Efficiency in Health Care (IQWiG). Acne: Overview 12. NHS. Causes: Acne 13. Kucharska A, Smurlo A, Sinska B. Significance of diet in treated and untreated acne vulgaris 14. British Skin Foundation. Acne 15. Chularojanamontri L, et al. Moisturisers for Acne 16. Meier L, et al. Clay jojoba oil facial mask for lesioned and mild acne – results of a prospective, observational pilot study 17. NHS. Treatment: Acne

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