What Is Acne? A Complete Guide to Understanding Your Skin

Acne is one of the most common skin conditions in the UK - and if you’re dealing with it, you’re far from alone. Around 95% of people in the UK experience acne at some point in their lives, and while it often begins during the teenage years, many adults continue to experience breakouts well into their thirties, forties, and beyond.

More than a cosmetic concern, acne can affect confidence and daily life. Understanding what acne really is - and what it isn’t - is the first step toward managing it effectively. This guide explains what happens beneath the skin when acne develops, why it occurs, what the different types look like, and when it’s worth seeking professional help.

What Is Acne?

Acne is a chronic inflammatory skin condition that develops when tiny holes in the skin, called hair follicles, become blocked. Each follicle is attached to a small oil-producing gland known as a sebaceous gland, which makes an oily substance called sebum. Sebum keeps the skin soft and protected, but too much of it can cause problems.

When excess oil mixes with dead skin cells, it can form a plug that blocks the follicle. The blockage traps oil and bacteria beneath the surface, leading to inflammation and spots. In simple terms, acne develops because of four main processes:

Increased oil (sebum) production, often caused by hormonal changes
Build-up of dead skin cells, which clog the follicles
Growth of normal skin bacteria (Cutibacterium acnes) inside the blocked pores
Inflammation, as the body’s immune system reacts to these blockages

If the top of the blocked pore is open to the air, it darkens and forms a blackhead. If it remains closed, it appears as a pale bump or whitehead. Once bacteria multiply within the blocked pore, the immune system responds and the area becomes red, swollen, and sometimes filled with pus.

Acne is typically described as mild, moderate, or severe. Mild acne involves mostly blackheads and whiteheads. Moderate acne includes more inflamed spots across the face or body. Severe acne features painful lumps deep beneath the skin, known as nodules or cysts, which can lead to scarring.

It’s important to remember that acne is not caused by dirt or poor hygiene. The blockages happen inside the follicles, where washing cannot reach. Over-cleansing or harsh scrubbing can irritate the skin and make acne worse.

Why Does Acne Happen?

Acne results from a combination of internal and external factors. Some people inherit an increased tendency toward oily skin or blocked pores, while others develop acne due to hormonal changes or external irritants.

Hormones play a major role. During puberty, rising levels of androgens such as testosterone stimulate the sebaceous glands to produce more oil. For women, hormone fluctuations before menstruation, during pregnancy, or around menopause can also cause flare-ups. Conditions like polycystic ovary syndrome (PCOS) are a common hormonal trigger.

Genetics can influence how sensitive your oil glands are and how easily your skin cells shed. If one or both of your parents had acne, you’re more likely to develop it and may experience more persistent symptoms.

Bacteria, specifically Cutibacterium acnes, are another factor. These bacteria live harmlessly on everyone’s skin, but inside a blocked pore they multiply and release substances that trigger inflammation.

Lifestyle and environmental factors can make acne worse. Stress, poor sleep, and high-glycaemic diets (those rich in sugar and refined carbohydrates) may increase oil production and inflammation. Certain medicines, including corticosteroids and lithium, can cause or worsen acne. Heavy cosmetics or thick sunscreens can block pores, and friction from items like helmets or tight clothing can irritate the skin.

Together, these influences explain why acne can vary so much between individuals - and why the same routine doesn’t work for everyone.

Types of Acne

Dermatologists classify acne by whether it involves inflammation.

Non-inflammatory acne includes blackheads and whiteheads, also called comedones. Blackheads, or open comedones, are small, dark-topped bumps where the pore remains open. Whiteheads, or closed comedones, are pale or flesh-coloured bumps sealed by skin. These are usually mild and not painful.

Inflammatory acne includes papules, pustules, nodules, and cysts. Papules are small, red bumps that can feel sore. Pustules look similar but have a visible white or yellow centre of pus. Nodules are larger, hard lumps beneath the skin, while cysts are deeper, softer, pus-filled lumps. Both can cause pain and often leave scars without treatment.

Many people experience a mix of these types at once - for example, blackheads on the nose and inflamed spots along the jawline. Recognising which you have helps guide the right care.

Common Myths About Acne

Because acne is so visible, myths about its causes and cures spread easily. Here are some of the most persistent misconceptions - and the facts behind them:

"Acne is caused by dirt." False. The blockages that lead to acne form inside hair follicles, not on the surface. Over-washing or harsh scrubs can damage skin and worsen irritation.
"Only teenagers get acne." False. Adult acne is common, particularly among women, due to hormonal changes.
"The sun helps clear acne." False. Tanning may hide redness, but UV light increases irritation and can worsen acne long-term, especially when using medicated creams.
"Toothpaste works on spots." False. Toothpaste ingredients can burn and irritate skin - it’s meant for teeth, not the face.
"Popping pimples makes them heal faster." False. Squeezing pushes bacteria deeper into the skin and raises the risk of scarring.

Understanding these myths helps people focus on safe, evidence-based approaches instead of quick fixes that often backfire.

Pharmacist Insight

"Many people think acne only affects teenagers, but we see adults struggling with it too - at all ages and stages of life. The key is understanding that acne is a medical condition, not a hygiene issue. With patience, consistent treatment, and good advice from a pharmacist or GP, most people can see real improvement," says Alessandro Grenci, Superintendent Pharmacist at Medino.

When to Seek Professional Help

Mild acne often responds to over-the-counter treatments such as gels or creams containing benzoyl peroxide, salicylic acid, or azelaic acid, along with a gentle skincare routine. However, some signs mean it’s time to seek professional support:

Your acne hasn’t improved after 8–12 weeks of regular use of pharmacy treatments
Spots are painful, inflamed or leaving scars
Acne is spreading to the chest, shoulders or back
It’s affecting your confidence or wellbeing

Pharmacists can guide you on choosing products, explain how to apply them effectively, and identify when a GP visit might be needed. A GP may prescribe stronger topical treatments, oral antibiotics, or, for women, hormonal therapies. Severe cases may require referral to a dermatologist for specialist medicines such as oral isotretinoin.

Early treatment prevents scarring and helps restore confidence. Acne is common - but it’s also highly treatable.

Key Takeaways

Acne is a medical condition involving blocked hair follicles, excess oil, bacteria, and inflammation. It’s not caused by dirt or poor hygiene, and it can affect anyone at any age. By understanding what happens inside the skin, you can choose treatments that target the real causes rather than myths or surface solutions.

Most people see significant improvement with patience, consistent skincare, and professional guidance. If your acne is painful, persistent, or affecting your daily life, talk to a pharmacist or GP. Clearer skin and renewed confidence are achievable with the right support.

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Written by Christian Jakobsson