Psoriasis is one of the most common skin diseases and affects about 5% of the population in the United States. It is also one of the most frustrating skin conditions because it typically not only affects the skin causing red, thickened, scaly plaques, it may also have numerous physical and psychological symptoms.
Up until recently, people believed that psoriasis was simply a skin disease without any other disease implications. Nowadays, we have learned that this is not true.
First, there are studies which report that patients with psoriasis are clinically depressed about 12% of the time or may have a of mood disorder including anxiety about 28% of the time. This tells us that this condition is not just skin deep.
There are also several other scientific articles showing that patients with psoriasis also have a higher risk of fatty liver disease, cardiovascular disease, and stroke when compared to the general population. Psoriasis can also have flare ups causing pain, itching, missed days of work, increased doctor’s visits, and increased spending on healthcare.
Psoriasis is caused by complex interaction between hereditary and environmental factors. One of the most powerful causes of psoriasis is from strong genetic factors. These factors lead to increased inflammation signals in the body called interleukins and dramatically increase the growth rate of skin cells leading to scaly, flaky, red, plaques. Sometimes medications or infections can trigger the disease. For some reason, certain drugs such as the blood pressure medication metoprolol, the antifungal terbinafine, lithium which is used for mood disorders, or oral steroids can cause a severe flare up of psoriasis. Infections such as streptococcal pharyngitis (strep throat) or HIV infection, or trauma/ injury to the skin (called the Koebner phenomenon), or stress may cause or worsen psoriasis. Certain dietary factors can also trigger flare ups of psoriasis. We recommend you review our blog post on this topic for more information as this was one of the most requested articles from our subscribers. In many other cases, the disease occurs without any particular trigger or inciting event.
There are different presentations of psoriasis which may seem like different diseases on the surface but are all just variations of psoriasis. The most common presentation of psoriasis is the presence of pink, thick, scaly plaques on the scalp, elbows, palms, soles, and knees. More than half of people with psoriasis will also have scalp psoriasis. Scalp psoriasis is sometimes related to dandruff or seborrheic dermatitis depending on the severity. Generally speaking, dandruff is limited to the scalp, mild, controlled with shampoos, and flares during the winter. Seborrheic dermatitis is more severe with involvement of other parts of the face including the eyebrows, ears, and beard areas. It may have a similar course as dandruff with intermittent flareups. Scalp psoriasis tends to be the most severe with ongoing raised, scaly, and red patches in the scalp that are resistant to treatment.
Sometimes, scattered coin-like lesions appear on the skin which is called Guttate psoriasis and this condition is usually caused by strep throat in an otherwise healthy person. Rarely, psoriasis can present as small pimples called pustular psoriasis.
Patients with any form of psoriasis are at risk for arthritis that may damage the joints called psoriatic arthritis. It is common in patients with psoriasis affecting up to 30%. It is more frequently seen in patients with nail psoriasis which leads to damage of the nail and yellow, thickened, discolored nails reminiscent to a nail fungal infection or the nails could also have small tiny pits along the surface. Psoriatic arthritis usually affects the hand joints but can cause pain in any joint. People usually experience long periods of morning stiffness, swelling, and pain within the joints.
An effective treatment can usually be obtained but everyone responds differently, and some patients may require more powerful treatments. Unfortunately, once the medications are stopped psoriasis may return as they control but cannot cure the disease. If ointments are used, they need to be applied regularly because once one treated area improves, sometimes a new spot pops up. Thankfully, there are many excellent treatments for psoriasis and the number keeps expanding due to advancing technology. They work by decreasing inflammation in the skin and normalizing the skin growth. In general, most treatments are combined. For example, a patient with severe psoriasis may be on light therapy and prescription ointments. Scalp psoriasis can be particularly difficult to treat since the scaling tends to be very thick.
Triggers such as strep throat should be treated with antibiotics if identified. Also, reviewing all new medications and stopping those that can cause or flare psoriasis should be considered. As mentioned before, if psoriasis starts after a new blood pressure medication is started the stopping it for a few months could help.
Typically, topical skin treatments are first line therapy if the disease is mild and not involving a large area of the skin. These include topical steroids which range from low, mid, and high potency. It is important to use liquids or foams in hair-bearing areas since ointments tends to be sticky and greasy. Steroid-alternative are ointments which contain tacrolimus or pimecrolimus are also available. There are useful in areas where topical steroids should be avoided including areas around the eyes or prolonged exposure to the face or sensitive areas of the body like the underarms or groin. Prescription-strength vitamin D ointments also improve psoriasis and are usually used in combination with topical steroids.
A different class of prescription psoriasis treatments that are different from steroids or prescription-strength vitamin D medications are called retinoids. The one that works best for psoriasis is called tazarotene. Sometimes the use of retinoids is limited as they may cause irritation and severe dry skin. There are also a few over-the-counter therapies which include salicylic acid and coal tar.
Once psoriasis becomes more severe covering a larger surface area of the body, it becomes too difficult, unrealistic, affects large areas on the scalp and/or nails making topical treatments difficult to apply or penetrate, or it would be dangerous to apply ointments over most of the skin surfaces. In this phase, once a patient has completed their initial therapy and not reached their goals, phototherapy is usually selected.
In the United States we use narrow band UVB therapy which targets the cells and helps “push” them out of the skin. Sometimes natural sunlight 10-15 minutes per day in the mid-day sun can improve active plaques too. Natural sunlight is completely different from the specialized form of prescription light therapy narrow band UVB therapy. Tanning beds are not recommended as they are linked to the development of malignant melanoma and again, like natural sunlight, is not as effective in targeting the inflammation in the skin. It is important to apply sunscreen to normal skin to avoid a sunburn in a flare up due to the Koebner phenomenon (psoriasis appearing in sites of injury) where the burn occurred.
The next step in therapy is usually an oral or injectable medication which include drugs help to combat the overactive immune system and inflammation present in psoriasis. There are many prescription treatments such as methotrexate, cyclosporine, acitretin, and apremilast. Oral or injectable medications are used to treat the inflammation of psoriatic arthritis since ointments do not penetrate and treat the deeper inflammation.
There are also injectable immune modulating therapies which include etanercept, adalimumab, infliximab, and other drugs which have come on the market in the last few years. Patients must have a thorough examination by their doctor as any of these medications may cause side effects and are not safe if certain medical conditions are present.
You should feel empowered to improve your skin with your own determination and willpower. Lifestyle and dietary modification can help psoriasis and do not require a visit to a doctor’s office. We refer you to our article entitled “Psoriasis and diet” for further information as many of the suggestions there can be incorporated into your everyday life.
- Dowlatshahi EA, Wakkee M, Arends LR, Nijsten T. The prevalence and odds of depressive symptoms and clinical depression in psoriasis patients: a systematic review and meta-analysis. J Invest Dermatol. 2014 Jun;134(6):1542-1551.
- Prussick RB, Miele L. Nonalcoholic fatty liver disease in patients with psoriasis: A consequence of systemic inflammatory burden? Br J Dermatol. 2017 Dec 13.
- Egeberg A, Skov L, Joshi AA, Mallbris L, Gislason GH, Wu JJ, Rodante J, Lerman JB, Ahlman MA, Gelfand JM, Mehta NN. The relationship between duration of psoriasis, vascular inflammation, and cardiovascular events. J Am Acad Dermatol. 2017 Oct;77(4):650-656.
- Fowler JF, Duh MS, Rovba L, Buteau S, Pinheiro L, Lobo F, Sung J, Doyle JJ, Swensen A, Mallett DA, Kosicki G. The impact of psoriasis on health care costs and patient work loss. J Am Acad Dermatol. 2008 Nov;59(5):772-80.
- Pacan P, Szepietouski JC, Kiejuo A. Stressful life events and depression in patients suffering from psoriasis vulgaris. Dermatol Psychosom. 2003;4:142–5.
- Nestlé FO, Kaplan DH, Barker J. Psoriasis. N Engl J Med. 2009;361:496–509.