How Common is Psoriasis?

Psoriasis  is one of the commonest skin diseases . It has the dubious distinction of having second place in prevalence  amongst all skin diseases, the first being acne vulgaris. Psoriasis is also one of the oldest skin diseases known to medical science.

Prevalence of Psoriasis

Global Prevalence of Psoriasis (Greb JE et al. Psoriasis. Nat.Rev.Dis.Primers doi:10.1038/nrdp.2016.82)

Genetic and environmental factors greatly influence the clinical development of psoriasis. This results in wide differences in the prevalence of this disease among different ethnic groups and in different parts of the world.

Patients with minimal clinical manifestations often do not  seek medical attention. In many third world countries, poverty, illiteracy, ignorance, and , in case of females, modesty may be preventing patients from approaching health care providers for diagnosis and management of the disease.Hence psoriasis may be much more prevalent than the studies indicate.

Most studies on prevalence are based on information from clinical examinations, interviews, census studies and mailed questionnaires.

Thus, estimates of the occurrence of psoriasis in different parts of the world vary from 0.1 to 3%.

Around 125 million people worldwide (up to 3% of the population) have psoriasis.

23% of people – that’s28 million – with psoriasis go on to develop psoriatic arthritis, a potentially debilitating type of joint disease, a complication of psoriasis.

Its prevalence in a hospital population was about 6% to 8.7% in two studies

In the United States, between 2 and 2.6% of the population is affected with psoriasis. That works around to approximately 7.5 million persons with psoriasis. Between 150,000 and 260,000 new cases of psoriasis are reported annually.

Four hundred people die annually from psoriasis-related causes in the US.

Approximately1.5 million people with psoriatic arthritis seek medical care each year in theUS.

Geographical & Racial Distribution

Psoriasis is more common in whites. The incidence of psoriasis is much lower in dark-skinned West Africans andAfrican-Americans than in light-skinned people of European ancestry. Incidence is also low in Japanese and Eskimos, and is extremely low to non-existent in Native Americans in both North and South America.

The prevalence of psoriasis in African Americans has been estimated at 0.7% based on 3860 consecutive patients seen in a private dermatology practice in Cleveland, Ohio. Gelfand et al(2005) confirmed these previous investigations that have suggested that psoriasis is less common in African Americans than in Caucasians. However, according to their  study, psoriasis was certainly not rare in African Americans as was previously thought of.  Their study showed the prevalence of psoriasis as 2.5% in Caucasian patients and  1.3% in African American patients.

In Africa, variations in the prevalence of psoriasis have been observed between West African countries such as Nigeria (0.8%) and East African countries such as Kenya (2.6%).

Age of Onset inPsoriasis

Psoriasis occurs in both children and adults and may appear at any age, although it is most commonly diagnosed between the ages of 12 and 35. A second peak appears between the ages of  60 to 69 years.

There have also been case reports of psoriasis appearing in infants within weeks of birth and in patients above the age of 70 years, but these are more of exceptions rather than the norm.

Approximately 10-15% of new cases begin in children younger than 10 years. Children tend to have more of the guttate variety of psoriasis than the plaque psoriasis compared to adults.The median age at onset is 28 years.

Females tend to develop psoriasis slightly earlier than males and those with a family history have an early age of onset.


Psoriasis occurs with almost equal frequency in males and females. Many studies have found higher prevalence among males while others vouch for a higher female prevalence. As the difference between the genders are not very prominent, we will settle for the equal frequency.

There may be another reason for the disparity in sex prevalence studies.

As females are more concerned about the condition of  skin and nails and are more aesthetically inclined than their counterparts, they must be approaching doctors more often with milder varieties of psoriasis.

Read more about Psoriasis

Psoriasis: A Brief History

Psoriasis is probably one of the longest known illnesses of humans and also one of the most misunderstood one. It was confused with leprosy till the 19th century.

The biblical term ‘lepra’ was actually applied to various cutaneous disorders including psoriasis, vitiligo, eczema, boils and alopecia areata. Some believe that  ‘tzaraat’ mentioned in the Bible represents psoriasis.

Hippocrates (460 – 377 BC) did describe a skin condition akin to psoriasis.

There are mentions in the literature about the term “psoriasis” as being  used by Aristophanes of Byzantium at the end of the third century B.C. But Aristophanes’ description  of the disease does not, however, correspond to our clinical picture of psoriasis.

Some historians, however, believe that  it was the Roman physician Galen who used the term “psoriasis vulgaris” for the first time, though not particularly for the exact entity .

The name psoriasis is derived from the Greek word psora which means to itch. In fact, before Hebra (see below) the term ‘psoriasis’ was used for many skin diseases where itching was a prominent feature.

In the first century, the Roman Sage Cornelius Celsus described a condition similar to psoriasis and classified it as the fourth variant of impetigo.

JosephJacob Plenck (Vienna, 1776) wrote of a condition similar to psoriasis as being amongst the group of desquamative (scaly or scale like) diseases. He did not dig deeper to differentiate it from other dermatological conditions.

Psoriasis was known as Willan’s lepra in the late 18th century after the English dermatologist, Robert Willan (1757 – 1812) recognised the disease as an independent entity. He identified two categories. Leprosa Graecorum was the term he used to describe the condition when the skin had scales. Psora Leprosa described the condition when it became eruptive.

Finally, it was in 1841 Ferdinand Hebra, a Viennese dermatologist improved on Willan’s notes and assigned the name  ‘Psoriasis’ to the disease for the first time in the long history of the disease.  It was Hebra who described the clinical picture of psoriasis as we recognise it today. The hereditary factor of psoriasis was already known by that time.

Psoriasis was further differentiated into specific types and effective remedies discovered during 20th Century.

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What is Psoriasis

Psoriasis is a non-contagious, genetic skin disease that results when faulty signals in the immune system prompt skin cells to regenerate too quickly, causing red, scaly lesions on the skin. It is now considered an autoimmune disease.

Scalp Psoriasis

Psoriasis is a lifelong disease like diabetes and hypertension. It typically causes dry, red, scaly lesions that can appear anywhere on the body, including the scalp, trunk, extremities and nails. Common areas involved are the extensor aspects like elbows, knees and the trunk.

Psoriasis is not contagious, that means you cannot catch it from someone else, nor can you give it to someone else, unless of course, they are your children.

Psoriasis Hands

The genetic origin means that if one of the parents has psoriasis, children stand a 10 to 25%chance of developing it. If both parents have it the odds for the children increase up to 50%.

The natural course of psoriasis is dotted with periods of waxing and waning. The lesions clear for sometime (called remissions), and, following some triggers, come back again. At times, when a treatment, like potent topical corticosteroids, is withdrawn suddenly, psoriasis may worsen or become generalised. This is known as are bound phenomenon and is something that has to be avoided at all costs.

Psoriasis has no complete cure, but with proper treatment and life style changes, psoriasis can be kept under optimum control and remission so as not to affect the quality of life of the patient.

The absence of a specific cure also means that psoriasis requires life long care and management.

Though there is no cure yet for the disease, recent introduction of new biological therapies has provided a fresh ray of hope for psoriatic patients for a better quality of life ahead. What is unique about biologic treatments is that they pinpoint certain immune responses that are involved in psoriasis, not the entire immune system, thereby creating fewer side effects for the patient and less damage to the immune system as a whole.

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Psoriasis 101

This is a short introduction to Psoriasis, the first of a series of educational articles on psoriasis by Dr Hanish Babu, MD, Dermatologist

Psoriasis plaques on hand
  1. Psoriasis is a chronic dry, scaly skin condition for which no cure has yet been found.
  2. Psoriasis is derived from the Greek word ‘psora’, which means itch.
  3. Psoriasis is not contagious.
  4. Psoriasis has a genetic basis, whereby in predisposed individuals certain triggering events or factors induce the body’s immune system to mistakenly speed up the growth cycle of skin cells.
  5. 125 million people worldwide (up to 3% of the population) have psoriasis. According to National Institute of Health, there are more than 7.5 million psoriasis patients in the United States.
  6. 10-30% of people with psoriasis may develop psoriatic arthritis with inflamed, stiff and painful joints.
  7. Studies have shown that people with psoriasis have almost the same reduction in quality of life as people with diseases such as cancer, diabetes or depression.
  8. Treatment for psoriasis is both topical and systemic and the choice and outcome of these treatments varies from individual to individual. Many patients suffer psoriasis in silence due to improper diagnosis and treatment.
  9. Most patients with psoriasis/psoriatic arthritis avoid social activities requiring body exposure due to embarrassment and fear of rejection.
  10. Recently, new biological therapies have been introduced giving new hope to people with psoriasis.

Read more about Psoriasis:

Topical Corticosteroids: Double Edged Swords!

Topical corticosteroids have revolutionised the treatment of inflammatory skin diseases, since they were introduced in 1952. They are very effective treatment options for many skin diseases and have revolutionised the management of eczema, allergies and other inflammatory skin diseases like psoriasis. Their effectiveness is prompt and most acute allergies can be cured within a few days. For chronic illnesses, like Atopic Eczema in children and psoriasis, they have to be used for a longer duration.

But, If not used with proper titre of dose and strength, they can cause damage to the skin, sometimes permanent. There are many unscientific formulations masquerading as anti-fungal creams and whitening or bleaching creams in the market, where one of the ingredient is potent or super potent steroid. Thus topical steroid creams are double edged swords, the use of which should be carefully titred according to their potency, stage of disease, age of the patient and site of application.

A knowledge of different classes of topical steroids according to their potency is important for everyone prescribing or using these effective and useful medications.

Classes of Steroids and Precautions
Classes of Steroids and Precautions

From the above it is clear that  topical corticosteroids  should be carefully chosen according to their potency, stage of disease, age of the patient and site of application. This is of paramount importance and all those who use these wonderful medications, including patients, pharmacists and doctors should be aware of their strengths and indications of use.

Topical corticosteroids come in several forms, including creams, lotions and ointments. Creams and solutions are a class below in potency than ointments. Ointments are greasy and preferred in chronic dermatitis and scaly diseases like psoriasis. Creams can be used in acute and subacute skin inflammation. Gels and lotions are preferred in hairy areas and scalp.

Side Effects of Topical Corticosteroids

Topical steroids have both topical (limited to skin) and systemic side effects.

Topical Side Effects of Topical Steroids Limited to Skin
  • Topical application of steroids causes thinning of the skin by causing atrophy of the skin layers.
  • Dilation of capillaries that are shown through the thinned skin, known as telengiectasia.
  • Stretching and splitting of the skin causing stretch marks or striae dystensiae.
  • Pimple like eruptions on the treated area, especially on the face, chest, back and limbs, called steroid acne.
  • The main problem with topical (and systemic steroids) is the rebound phenomenon or exacerbation of the lesions that occur if the steroids are suddenly stopped or withdrawn. A localized form of psoriasis can become generalized or a generalized form can get precipitated as pustular or erythrodermic forms when steroids are withdrawn.
  • Higher strength steroids should be avoided on the face, especially near eyes, on the body folds and near the genital organs. Steroids used near eyes for prolonged duration have been shown to cause cataract formation in the eyes and glaucoma.
  • Steroids are best avoided in the presence of infection as these can exacerbate infections.
  • Other topical side effects of topical steroids include easy bruising, purpura, skin ulceration, non healing of ulcers, exacerbation of infections, perioral dermatitis, rosacea, hypo pigmentation, hyper pigmentation, and excessive hair growth. Mistaken application of steroids on ring worms cause changes in morphology and spread of the fungal infection, known as tinea incognito.
Systemic Side Effects of Topical Steroids
  • Adrenal Suppression. Because of the absorption of potent steroids into the blood stream, the adrenal glands could become suppressed and their production of normal steroids will suffer as a result. This can have far reaching effects on the body. If prolonged, this can produce a cushingoid (moon like) face in patients and cause other systemic effects.
  • Tachyphylaxis.The body develops resistance to the topical application after some time.
How to Avoid Topical Steroid Side Effects
Unscientific Steroid Combinations
Unscientific Steroid Combinations are better avoided
  1. Topical Steroids are wonder drugs for many skin diseases like eczema and skin allergies but should be used only under supervision of a skin specialist or a modern medicine doctor who is trained to use it.
  2. Never buy steroid containing creams directly from pharmacy
  3. Avoid using fairness, whitening or bleaching creams from saloons, parlours and unlabelled sources. These may contain very strong steroids and cause serious damage to your skin.
  4. Avoid using so called anti-fungal creams containing steroids. When in doubt, consult a skin specialist before using such creams.
  5. Potent and super-potent steroid creams should only be used under the supervision of a skin specialist.
  6. Never use steroid containing creams in the presence of infection or if diagnosis is not sure.
  7. Use appropriate graded strength according to severity, age, site of involvement.
  8. Gradual withdrawal and replacement with safer creams should be resorted to.
  9. Superpotentà Potent à Moderate à Least Potent.  Shift down as the condition improves.
  10. Application free interval: 5-7 days after every two weeks of application helps avoid side effects.
  11. Never use higher strength topical steroids in infants and children.
  12. Avoid moderate to superpotent classes of topical steroids in sensitive areas like face and body folds.
  13. Once acute phase is under control, shift to steroid sparing calcineurin inhibitors like Tacrolimus, Pimecrolimus.

The information given in this article is for educational purpose only so that patients are aware of the options available for diagnosis and treatment of common skin, hair and nail diseases. No diagnosis should be made or treatment undertaken without first consulting your dermatologist. If you do so, the author will not be responsible for any consequences. The images provided are for illustration purpose only and should not be reproduced without the consent of the author.

About the Author of Skin Care Tips from Dermatologist: Dr Hanish Babu, MD
Dr Hanish Babu, MD, Dermatologist, Sharjah and Ajman, UAE
Dr Hanish Babu, MD

Dr Hanish Babu, MD is a dermatologist with more than 3 decades of experience in treating skin and sexually transmitted diseases in UAE and India. He has been practicing in UAE since last 22 years. He is a respected speaker during the Continuing Medical education Programmes for doctors, medical students and paramedical staff and is also a Stress Management Trainer. He organises group therapy sessions for patients with psoriasis, eczema and vitiligo.

He is available for consultation at Cosmolaser Medical Centre in Samnan, Sharjah (06 5678 200) from 10 am – 2 pm and at City Medical Centre, Al Bustan, Ajman (06-7 441 882) from 4.30 pm – 9.30 pm.

Visit his personal website for more details and for educational articles on Skin, hair, nail and sexually transmitted diseases. Click here to Book an Appointment with dermatologist Dr Hanish Babu, MD