Hairs are formed within the skin in tiny structures known as hair follicles. The word folliculitis describes inflammation of hair follicles and may happen anywhere on the body. The term folliculitis barbae is inflammation of hair follicles in the beard area (‘barba’ is the Latin word for beard).  

• Folliculitis barbae - printable version

Folliculitis decalvans is a rare chronic (long term) inflammatory condition of the scalp. Very rarely it can affect other hair-bearing skin such as the beard, armpits, pubic area and legs. The prolonged inflammation that usually occurs leads to scarring. Folliculitis decalvans is derived from Latin and means inflammation of the hair root associated with hair loss.

Folliculitis decalvans is not contagious and is not a type of skin cancer.

• Folliculitis decalvans - printable version

Fox-Fordyce disease is a rare skin disorder affecting the apocrine sweat glands. These are special sweat glands found in the armpits, genital region and breasts that produce a more dense secretion than the normal or ‘eccrine’ sweat glands found elsewhere on the body. Patients with this condition experience itchy bumps on the skin around the hair follicles. 

• Fox-Fordyce disease - printable version

Frontal fibrosing alopecia is a form of scarring hair loss affecting the hair margin on the front of the scalp. This happens due to inflammation and destruction of the hair follicles. There may also be hair loss from the scalp near the ears and from the eyebrows. Sometimes hair loss can also occur from other parts of the body, but this is less common. FFA occurs mostly in white postmenopausal women but can occur in premenopausal women, men, and people of other ethnicities. Frontal fibrosing alopecia is thought to be a variant of another condition called lichen planopilaris.

• Frontal fibrosing alopecia - printable version

Fungal infections of the nails are also known as dermatophytic onychomycosis, or tinea unguium. The responsible fungus is usually the same as that that causes athlete’s foot – a common infection of the skin of the feet, especially between the toes. In athlete’s foot the responsible fungus lives in the keratin that makes up the outer layer of the skin. When the fungus spreads to the keratin of the nails, the result is a fungal nail infection. 

• Fungal infections of the nails - printable version

Granuloma annulare is an uncommon skin condition, which most often affects children and young adults but can occur at any age. It is twice as common in women as in men. The reason for this is unknown. 

It usually presents as groups of small firm bumps in the skin which come together to form a characteristic ring shaped (annular) patch. These typically occur on only one or two sites of the body, often overlying bony areas such as the back of the hands, the feet, elbows or ankles. 

• Granuloma annulare - printable version

Guselkumab is a biologic medicine that has been designed to treat psoriasis. It works by specifically targeting a chemical messenger (known as a ‘cytokine’) in the body called ‘interleukin-23’ (IL-23). We know that IL-23 is one of the main causes of inflammation in psoriasis, and by blocking it guselkumab can improve symptoms of psoriasis. 

• Guselkumab - PRINTABLE VERSION

A ‘haemangioma’ (Greek for blood-vessel-growth) of Infancy is a benign (not cancerous) overgrowth of blood vessel cells that is self-limiting (will stop growing without treatment). The term ‘strawberry naevus’ or ‘strawberry haemangioma’ is used for a haemangioma that look similar to a strawberry.

• Haemangioma of infancy - printable version

Hailey-Hailey disease is also known as familial benign chronic pemphigus. It was originally described by the Hailey brothers. It is a rare inherited skin condition in which there are red scaly areas that can be itchy and sore, that can lead to superficial blisters and eroded (broken) areas of the skin. This usually affects the folds of the groin, armpits, neck and under the breasts. The condition flares intermittently and tends to come and go. Many patients are able to lead full and normal lives, with their condition being a nuisance rather than a serious problem. Some people are more severely affected and experience more persistent painful raw areas of the skin with development of superficial blisters.

• Hailey-Hailey disease - printable version

Female pattern hair loss (FPHL) has also been called androgenetic alopecia. It is the most common type of alopecia (hair loss) in women and the severity can vary.

• Hair loss - female pattern - printable version

Male pattern hair loss (MPHL) is the most common type of hair loss in men. It is also known as androgenetic alopecia. It affects about 50% of men over the age of 50.

• Hair loss - male pattern - printable version

Hand dermatitis is also called hand eczema. It is common and can affect about one in every 20 people. It can start in childhood as part of an in-built tendency to eczema, but is commonest in teenagers and adults. Hand dermatitis may be a short-lived, transient problem. However, in some people, it lasts for years and can have a great impact on daily life.

• Hand dermatitis - printable version

Head lice are very common. They are small (adult lice are the size of a sesame seed) grey-brown insects that live only on human scalps. They cannot fly or jump; neither can they burrow into the scalp. They can affect anyone, with long or short hair, no matter how clean the hair is.

• Head lice - printable version

There are two herpes simplex viruses that cause skin infection. They are called herpes simplex type 1 and type 2. They can be transferred from person to person by direct skin to skin contact with the affected place when enough virus is present. This is often a lesion or sore but transmission may also occur at other times, perhaps when there is only an itch or tingle in the area. The most common places of infection are the mouth (known as ‘cold sores’), followed by the genital area (genital herpes) and the hands. Most people are only infected in one area and are unlikely to transfer the infection to other parts of their bodies. 

Infection may be followed by symptoms, such as sores or blisters, within a few days but some people will not notice anything for months or years. Others are carriers who never have symptoms. The virus remains dormant in the sensory nerves close to the place of original infection.

Reactivation may result in more blisters nearby, on skin that is served by the same nerves (dermatome). The frequency of recurrences varies from person to person. For some people symptoms appear several times a year, in others rarely or never.

• Herpes simplex - printable version

Hidradenitis suppurativa is a long term, recurrent, and painful disease in which there is inflammation (redness, tenderness and swelling) in areas of skin containing apocrine sweat glands. These glands are found mainly in the armpits, breasts and groins. Within HS there is a blockage of the hair follicles. This causes a mixture of boil-like lumps, areas leaking pus, and scarring.Hidradenitis suppurativa is a long term, recurrent, and painful disease in which there is inflammation (redness, tenderness and swelling) in areas of skin containing apocrine sweat glands. These glands are found mainly in the armpits, breasts and groins. Within HS there is a blockage of the hair follicles. This causes a mixture of boil-like lumps, areas leaking pus, and scarring.

Hidradenitis suppurativa tends to begin around puberty age, and is more common in women. It is estimated to affect about 1% of the population.

• Hidradenitis suppurativa - printable version

Hirsutism refers to excessive growth of dark, thick and coarse hair in an individual (usually female) in a male pattern. Commonly affected areas are upper lips, chin, central chest, midline of the stomach, lower back, buttocks and front of thighs. Hirsutism affects approximately 10% of women in Western societies and is commoner in those of Mediterranean or Middle-Eastern descent.

If the excessive hair is generalised and not in a gender specific pattern, the term is ‘hypertrichosis’, which means increased (‘hyper’) hair (‘trichosis’). In this leaflet we will only discuss hirsutism.  

• Hirsutism - printable version

Our hands come into daily contact with many substances such as household detergents and cleaning products; personal cleansers including soaps, shampoos and wet wipes; food components such as fruit acids and plant chemicals and water.These can take away the protective oils that keep the skin moist, leading to chapping, dryness, and irritation. Frequent contact with water is one of the commonest causes of skin irritation. Once the skin on the hands is irritated and damaged, it is prone to further damage and a vicious circle is set up leading to hand dermatitis, or making existing dermatitis worse. Dermatitis in this leaflet refers to any rash that affects the skin including eczema, psoriasis, allergic contact or irritant contact dermatitis.

• How to care for your hands - printable version

The Lymphatic System

Lymph nodes are part of the lymphatic system, which is a network of tiny tubes that carry a colourless fluid called lymph through the skin and deeper parts of the body.  Lymph fluid contains immune cells (lymphocytes) nutrients and waste materials.

 Lymphatic Vessels

It bathes the cells of the skin and internal organs and   drains into lymphatic vessels then larger ducts in the neck before joining the blood stream near the heart (see Figure 1).

Lymph Nodes

Lymph nodes (‘glands’) are small oval nodules and contain millions of infections fighting lymphocyte cells.  They are found at intervals along the lymphatic vessels like ‘beads on a string’ (see Diagram 1). The lymph nodes filter out harmful organisms and abnormal cells before the lymph reaches the blood stream. Lymph nodes can only be felt in certain areas:

• head and neck
• arms
• axilla (armpit)
• inguinal area (groin)
• back of knees

Lymph node are usually too small to feel except in slim people when they can be felt as smooth pea-sized lumps in the groin. Another common exception is when people get a sore throat or an ear infection, which can make the neck lymph nodes enlarged, painful and tender.

Lymph nodes can also become enlarged if cancer cells lodge in them. In this case, they are usually painless.

• How to check your lymph nodes - printable version

Hydroa vacciniforme is an extremely rare skin condition in which there is an abnormal sensitivity of the skin to sunlight (photosensitivity). It is neither infectious nor dangerous, but it can restrict an affected person’s lifestyle, particularly during the summer months and on holidays.

The term hydroa is possibly from the Greek for ‘watery eggs’, a reference to the blisters that characterise this condition; vacciniforme derives from the Greek for the ‘pox-like’ permanent scars (resembling large deep chicken pox scars) that result when the blisters heal.

Hydroa vacciniforme usually affects children aged 3-15 years, and is more common in females than males. In boys, hydroa vacciniforme may develop at a later age than in girls, and go on for longer.

• Hydroa vacciniforme - printable version

Hydroxycarbamide, formerly known as hydroxyurea, affects cells that are dividing rapidly, such as the skin cells in psoriatic plaques and the blood cells in the bone marrow. It is mainly used for cervical and blood cancers, but is also used to treat psoriasis. It is known as a ‘cytotoxic’ medicine, meaning that it interferes with cell growth. 

• Hydroxycarbamide - printable version

Hydroxychloroquine is one of several antimalarial drugs that have anti-inflammatory effects useful in other diseases.

Hydroxychloroquine is particularly effective for systemic lupus erythematosus (SLE) and discoid lupus erythematosus (DLE). By reducing inflammation, hydroxychloroquine can decrease pain, swelling and stiffness of joints, and improve or clear some rashes.

• Hydroxychloroquine - printable version

Hyperhidrosis means excessive sweating. It can be localised or affect the whole face and body.

Sweating is controlled by the brain, which sends signals along nerves called “sympathetic nerves” to the small sweat glands in the skin. These nerves are part of the “autonomic nervous system” which controls many unconscious body functions.

Increased sweating is a normal response to a rise in body temperature, and to emotions such as anxiety.

A treatment which reduces sweating is called an antiperspirant. This is different from a deodorant, which reduces odour, usually through an antibacterial effect. The two are often combined in the same product.

• Hyperhidrosis - printable version

Ichthyosis is the term used to describe continual and widespread scaling of the skin. It may be inherited (genetic) or acquired during life. The inherited forms are rare, generally present from infancy, and are usually lifelong conditions. Acquired ichthyosis can develop at any age due to a number of medical problems, such as kidney disease.

The commoner forms of inherited ichthyosis are mild and do improve during warmer weather. There are a number of very rare conditions where ichthyosis occurs with problems in other systems of the body. Each of the major types of ichthyosis will be discussed briefly, followed by an outline of the management.

• Ichthyosis - printable version

Imiquimod is a cream that when applied to the skin activates the immune system to recognise abnormal cells and causes inflammation which removes them.

In the UK, two strengths of Imiquimod cream are available, a 5% cream (trade name Aldara®) and a 3.75% cream (Zyclara ®).

• Imiquimod cream - printable version

This leaflet has been written to give you information aboutimmunisations (vaccinations), which may affect you when you are taking medicines that act by suppressing the immune system. This includes information about vaccinations which are:

1.    Recommended before you start immune suppressing medicines

2.    Safe for you to have while you are taking this treatment

3.    Need to be avoided 

• Immunisation - printable version

Impetigo is a bacterial infection of the surface of the skin. In the UK, it is the most common skin infection seen in young children, but may be seen in people of any age. 

• Impetigo - printable version

Infliximab is a powerful anti-inflammatory drug that has been designed to resemble normal human molecules, and is therefore classed as a “biological” treatment. It reduces inflammation by inhibiting the activity of a chemical (“cytokine”) in the body called ‘tumour necrosis factor alpha’ (TNF-alpha).

• Infliximab - printable version

This is a procedure involving the injection of a steroid solution directly into the skin lesion or immediately below the skin, with the aim of improving its appearance and/or reducing symptoms such as itch or pain. The steroid preparation most frequently used in this procedure is called triamcinolone acetonide, and is sometimes referred to as “intralesional triamcinolone”.

• Intralesional steroid therapy - printable version

Iontophoresis (pronounced eye-on-toe-for-ree-sis) is a safe and effective treatment that can be used to reduce excessive sweating (hyperhidrosis) of the hands, feet, underarms and face (if the necessary attachment is available to go onto the machine).

• Iontophoresis for hyperhidrosis - printable version

Isotretinoin (brand name Roaccutane) belongs to a group of drugs called retinoids, which are closely related to vitamin A. It works in a variety of ways, targeting different factors that cause acne including the production of sebum (an oily substance produced by the skin) and the production of keratin (outer scales of skin) that block the pores of the hair follicle.

• Isotretinoin - printable version

Ixekizumab is a biologic medicine that has been designed to treat psoriasis. It works by specifically targeting a chemical messenger (known as a ‘cytokine’) in the body called ‘interleukin-17A’ (IL-17A). We know that IL-17A is one of the main causes of inflammation in psoriasis and psoriatic arthritis, and by blocking it ixekizumab can improve symptoms of these conditions. 

• Ixekizumab

Junctional epidermolysis bullosa (JEB) is a rare inherited (genetic) skin disorder. It is not an infection, it is not contagious and it is not due to an allergy. It is different from the other forms of epidermolysis bullosa (EB), which include epidermolysis bullosa simplex, dystrophic epidermolysis bullosa and Kindler Syndrome. Individuals who have JEB will not develop one of the other types of epidermolysis bullosa at a later date.

The skin of those who have JEB is fragile and minor everyday knocks and friction, such as rubbing or scratching, cause blisters or raw areas. There are three main sub-types of JEB: severe, or Herlitz, JEB; intermediate, or non-Herlitz, JEB and JEB with pyloric atresia. JEB varies in severity, from relatively mild with a normal lifespan, to the most severe form in which babies may not live beyond their first birthday.

• Junctional epidermolysis bullosa - printable version

JXG is a skin lump caused by an excess of cells known as histiocytes. It is rare and occurs mainly in infants and young children, although about 10% occur in adults. It is not known what causes this condition. It is not a type of cancer. 

• Juvenile xanthogranuloma - printable version