What is psoriasis?

Psoriasis is a chronic inflammatory disease that affects the skin and joints. During an outbreak, raised patches of dry skin – red on fair skins and white on dark skins  – appear, especially on the skin in the area around the joints, such as the knees and elbows.

In 30% of cases psoriasis affects the joints themselves that become stiff (especially the lower back) or swollen. Some people also complain of itching, especially at night.   

The disease typically occurs  

  • at around the age of 20: type 1 psoriasis of which there is often a family history; 
  • or around the age of 40: type 2 psoriasis that often appears at times of major stress. 

Psoriasis affects about 3% of the population. It is not a contagious disease.  

Your care and treatment


A dermatology consultation is often enough to make or confirm a diagnosis. After which the patient can be referred to the Erasmus Hospital’s Clinic for Inflammatory Dermatological Diseases where they will be seen by a dermatologist specialised in psoriasis, either for an individual consultation or a joint consultation with a rheumatologist if joints are affected. As psoriasis can be associated with a chronic intestinal inflammatory disease (e.g. Crohn’s disease), a  gastroenterologist may also be brought in.   

Stress, smoking and being overweight or obese are all pro-inflammatory factors and favour psoriasis outbreaks. For this reason and depending on your profile, consultations with a psychologist, tobaccologist and/or dietician may be suggested.   


Treatment of psoriasis depends on the extent of the symptoms and whether or not a joint is affected.   

  • A cortisone cream, vitamin D supplement and/or localised phototherapy sessions for the hands and feet can be enough to treat small skin surfaces.  
  • Immunosuppressive treatment and/or phototherapy sessions in a cabin can treat  larger skin surfaces, with or without affected joints. 
  • Monthly or quarterly biotherapy (auto)injections are reserved for cases of refractory psoriasis, with or without affected joints. The patient can learn to self-inject, use the services of a visiting nurse or attend the Wound Care Clinic (located at the Erasmus Medical Center) where a member of the nursing staff will give the injection.   

Examinations and follow-up 

To be reimbursed, the candidate for immunosuppressive treatment or biotherapy must first have a complete blood test and lung X-ray to rule out the possibility of tuberculosis  (= immunosuppressants are contraindicated).  

If the treatment is initiated, patients must return one month later for a consultation to check whether their body is responding to and tolerating the immunosuppressant or biotherapy. If all is fine, quarterly monitoring is instigated.   


Daily skin hydration with appropriate products is an inherent part of psoriasis treatment. No aggressive aesthetic treatment (hair removal, scrub, tattooing, etc.) of the skin must be undertaken without medical advice, especially if the psoriasis is not under control. While the chlorinated water of swimming pools is not recommended, seawater and sun (with sun protection) generally have a positive effect on psoriasis rashes.



Dermatologists at the Erasmus Hospital initiate or participate in epidemiological (on the basis of a questionnaire), clinical (new treatments) or academic research projects on psoriasis.