A mole is usually a mid or dark brown flat mark (a junctional naevus), or a dome-shaped brown or flesh-coloured bump (a dermal naevus). It should be neither itchy nor bothersome. You may have numerous moles, and they may run in your family. They may have been present for as long as you can remember, or since birth, although new moles can appear throughout childhood and even into your 20s, especially after recent sun exposure. Certain skin types such as those with pale skin, blue eyes and red or blond hair, and who are likely to easily burn, are likely to be more at risk of concerning changes to moles.

This is a condition that mainly affects the corners of the mouth rather than the rest of the lips. The main symptoms include swelling and redness, blistering, and crusting or cracking in the corners of the mouth. It’s also sometimes known as angular stomatitis. It may be painful and can be caused by a number of factors. Some forms of angular cheilitis may be caused by sweat and saliva build-up. This causes changes in pH on the skin and can lead to a fungal infection in the corner of the mouth. There can also be bacterial or viral infection present. It is usually bilateral and symmetrical although occasionally it may affect one side of the mouth only and may sometimes spread to cause impetigo or oral thrush.

Actinic keratoses (or solar keratoses) are small red flakey marks on your skin in response to long-term sun damage. They appear many years after sun exposure on sun-exposed areas such as the top of forehead or crown of the head, tops of ears, forearms, hands and lower legs, and so are more common in older people. They feel like rough patches like sandpaper, and yellow or orange scales can appear that resemble tiny cornflakes. The surrounding skin may be pink or red, and there might other evidence of sun damage such as deep wrinkles, large freckles or brown blotches. They don't usually cause any symptoms beyond a mild itch or soreness, but some people feel self-conscious that they look unsightly.

Acne vulgaris, also known as pimples, acne, spots or zits, is very common, usually starting in the teenage years and continuing up to the age of 30. About 80% of teenagers suffer some degree of acne. Mild untreated acne typically takes several years to settle but severe acne can scar the skin for life if untreated. It coincides with the hormonal changes of puberty, and women may suffer into adulthood with hormonal changes in their menstrual cycle. Hormones affect the amount of oil (sebum) produced by glands next to hair follicles so the skin becomes very greasy, and these follicles then become blocked and inflamed. Acne can cause blackheads, whiteheads or pustules, or more inflamed lesions including red and sore cysts and larger nodules, which are more likely to cause long-term scarring. Acne usually affects the face - the T-zone is typical in teenagers (forehead, nose and chin), or the muzzle distribution in early adulthood, which includes the upper lip, chin, jawline and neck. However it can also affect the back and chest.

A yeast called candida can be responsible for infections in the mouth, on the skin and around the genital area. Doctors call the infection candidiasis, but it’s known to most as thrush. Yeast infections are more common in people who are pregnant, those taking antibiotics, or those who are prone to infections due to other medical conditions, such as poorly controlled diabetes or immunosuppression. It is common in the mouths of children and babies, and can be common in people who wear dentures. Most women will suffer from a vaginal thrush infection at some point in their life. Yeast infections are easily treated with antifungal medications. Depending on where your infection is and how widespread, these come in the form of oral drops, pessaries, creams or tablets.

Under its fancy Greek title of xeros (dry) and derma (skin), dry skin can be intensely itchy. It feels rough and flakes easily. Cracks and redness can form in more severe cases. It affects both sexes and is more common in Caucasian skin than those whose skin has a higher oil content, such as Afro-Caribbean or Mediterranean skin types. Children can be particularly at risk, and this may take the form of eczema - where inflammation of the uppermost layer of skin causes dryness, and this is most likely to appear on the insides of elbows or the backs of knees. Eczema may run in families or go alongside asthma or hay fever. Dry skin is a variant of normal skin and is not contagious.

Warts and verrucas are caused by a harmless viral infection in the skin called the human papilloma virus (HPV). HPV causes keratin, a hard protein in the top layer of the skin, to grow too much, giving the typical roughened texture of a wart. There are more than 60 different types of viruses known to cause warts, this includes genital warts. They are increasingly common through childhood and adolescence but then their frequency drops drastically again on reaching adulthood. Warts often look different depending on where they are on the body and how thick the skin is, and a wart on the sole of the foot is called a verruca. What do they look like? Warts on the hands are found most frequently around the nails and on the fingers and are often shaped like a cauliflower, whereas verrucas are seen most commonly on the ball of the foot as areas of flat, thicker skin with a harder edge around a softer centre.

Vitiligo occurs when pigment (melanin) is lost from areas of skin, leaving behind white patches. The patches can grow in size and merge. These patches may be a little itchy but are not otherwise bothersome. The main complaint is the appearance of these patches, and the loss to self-confidence that comes with it. This requires specialist attention to treat, with the aim of stopping new patches forming, and if it's caught early enough, there's the possibility of reversing white areas to allow pigment to gradually come back. For this reason, it's important to see your doctor.

A shingles rash is caused by a virus called herpes zoster, and starts as tiny red bumps or blotches that then become weeping blisters (known as vesicles). This most often appears on the chest, back, stomach, neck or face. People sometimes notice a tingling or burning in the days before the rash appears, and may have a headache, mild fever or feel otherwise unwell. It is distinctive in that it will only appear on one half of the body, and usually only covers a small area. This virus was originally caught as chickenpox (varicella zoster virus), usually in childhood. While your body recovers from this, the virus lays asleep, or dormant, in the nerves and is reactivated under stress or illness, usually in those over 60 years old. Following the pathway of nerves means the virus is only activated from the nerves leading off the spine to one side or the other - a so-called dermatomal distribution.

This is a rash where the skin becomes inflamed, appearing on greasy areas with lots of sebaceous glands - on the cheeks, between eyebrows, the folds next to the nose and the chin, and also on the chest or scalp. Red, greasy, scaly or flaky patches are common and little red bumps known as papules may appear. It can cause a mild itch but it's that appearance prompts most sufferers to seek treatment. It is considered to be a type of eczema, but can also overlap with psoriasis and rosacea. Stress, tiredness and cold weather can prompt flare-ups in those susceptible. An overgrowth of a usually harmless yeast (posh name: Malassezia) is thought to be part of the cause, so treatment focuses on eradicating this and dampening down inflammation using a combined antifungal and mild steroid cream.

An SCC (squamous cell carcinoma) is usually a firm pink or red lump and typically occurs in sun-exposed areas like the face, ears, forearms and hands, shoulder, upper chest and back. It might feel tender to press, it may develop a solid horny lump sticking up and it can sometimes ulcerate, giving a wet appearance. This grows slowly over weeks, months or even years. It usually occurs in people aged over 50, in response to years of sun damage. While skin cancers all develop in response to sun damage, and similar risk factors make some more susceptible than others, there are different types of skin cancer. Melanoma is the most well-known, but actually the less common. This is where a new mole appears or an existing mole changes. SCC is a different process and doesn't usually start as a mole.

Psoriasis is a long-term condition that causes thickened patches to appear on the skin. It can only affect the scalp, or you might have other patches on your body. It can be intensely itchy and in a mild form, may cause red patches, usually at the back of the head and extending to the neck or behind the ears. In a more severe form, thickened plaque may cause temporary loss of hair, and this requires stronger and more prolonged treatment.