Smoking and Psoriasis

A report on tobacco smoking and its relationship to psoriasis.

Let me begin by saying that whether or not cigarette smoking has any effects on psoriasis, it would probably be better if you quit smoking, or never start smoking. The health effects of smoking cigarettes are well-known and much more likely to do permanent harm than is psoriasis. As Jerry J. once said, “Quitting smoking is a far more important step toward future health than anything related to psoriasis.”

Also let me say that this article will not be addressing any possible effects marijuana smoking might have on psoriasis, other than to say that there have been exactly zero medical articles published examining that issue. Therefore, anyone who might claim that marijuana has some known effect on the disease process is probably wrong.

Now then, does smoking have an effect on psoriasis? The answer isn’t a simple yes or no.

One thing which is absolutely certain, however, is that no studies have been published in the major medial literature since 1965 which address the question of whether or not quitting smoking will help psoriasis. Not a one. If you are reading this looking for a more-or-less definite answer to that question, I’m afraid you’ll largely be disappointed. I was disappointed, too, but realize there may be several levels of difficulty in setting up a clinical study which might be able to answer the question. See the section “The Personal Touch,” below, for one attempt at an answer.

What do the online abstracts of medical literature say, if not the above? Well, as a whole, in the broadest view, it says that psoriasis is “associated with” smoking. Since 1994, this has been used as an assumption in some studies of psoriasis (and other skin diseases) and smoking.

But that doesn’t really mean much by itself. It certainly doesn’t mean that all smokers will develop psoriasis. Or that psoriasis will vanish when a patient quits smoking. There are plenty of non-smoking psoriatics in the world.

Surprisingly, the earliest study I found (1990) which made an attempt at testing the association found none at all.[1] This could have been due to a number of factors, including location, the fact that they were looking for alcohol associations primarily, or that it was done on men (this makes a difference, as we shall see).

I found only two other clinical studies which actually asked the general question, “is psoriasis associated with smoking?” Both were published in 1992. Mills et al[2] found that if you smoke, you were more than twice as likely to have psoriasis as the general population, and found almost four times the number of ex-smokers among psoriatics as was expected. These researchers also found that if you smoked more than a pack a day (twenty cigarettes), you’d be over five times as likely to have psoriasis as normal.

Later in 1992, Naldi et al[3] found that among people with a new diagnosis of a skin disease, smokers were twice as likely to be freshly-diagnosed with psoriasis than other diseases, if they smoked more than fifteen cigarettes a day.

Now, I can’t say that these two studies were “definitive” in any way, and I can’t find any more basic research on the general question of psoriasis and smoking (more specific studies, yes, see below). But it appears from later articles that the association between psoriasis and smoking has been fairly firmly established. Some quotes from these later abstracts:

“Psoriasis is largely a disease of smokers…” (1994)[4]

“Other factors that have been reported to affect the course of psoriasis include… smoking…” (1994)[5]

“Several factors have been identified as being associated either with causation of psoriasis or with triggering exacerbations or remissions, including… cigarette smoking…” (1998)[6]

“The aggravating role of… smoking is well known.” (1999)[7]

“[Psoriasis] is associated with… smoking.” (1999)[8]

“Psoriasis is believed to be genetically linked but can also be triggered by … smoking” (2000)[9]

At least one study has also found that some cancers, especially those related to smoking or alcohol, are associated with psoriasis.[10] This appears, though, to simply be more evidence that psoriatics smoke more than the general population. However, another study found that smokers who undergo PUVA have a higher occurance of a certain type of DNA damage (which might lead to cancer) than non-smokers.[11] This might point at a higher risk of cancer among smoking psoriatics using PUVA than non-smoking psoriatics using PUVA, so if you’re undergoing PUVA therapy and you smoke, you might consider speaking with your dermatologist about this.

Male/Female Differences

While it is, apparently, true that psoriatics in general smoke more than normally-skinned folk, this is, it appears, even more true of women.[12] In another study among women with psoriasis, smoking was found to be a risk factor for the disease, but smoking was not found to be associated with the severity.[13] This would indicate that smoking is a risk for bringing on the first symptoms of psoriasis, but not a factor making the disease worse, at least in women.

Two other studies speak to sexual differences in smoking as it relates to psoriasis. One says that current smoking is associated with psoriasis in women, while being an ex-smoker is associated with psoriasis in men.[14] The other study found that women who smoke were about twice as likely to be hospitalized for psoriasis as non-smoking women.[15]

Palmoplantar Pustulosis

Palmoplantar Pustulosis (PPP) is a form of pustular psoriasis localized to the hands and feet. This form of psoriasis has been very highly correlated with smoking in some studies:

· A Swedish study found that 94% of the patients with PPP were smokers when the disease began.[16]

· A Japanese study found twice the average number of smokers in male PPP patients, and found that nearly four times as many female PPP patients smoked than average.[17]

· A study published in the East African Medical Journal found a similar relationship between smoking and PPP in developing countries as for Western countries.[18]

· Another Swedish study found that 56 of 59 PPP patients were smokers or ex-smokers, and that all of those 56 had started smoking prior to PPP showing up.[19]

· And, an Italian study found the odds that a person smoked was ten times higher in patients with pustular psoriasis in general (not necessarily PPP) versus the normal population.[14]

Yet another study from Sweden on PPP and smoking may point towards a mechanism for the correlation. Certain types of cellular receptors are greatly affected by nicotine, and can have large effects on the functioning of the cells they reside in. In PPP patients who smoke, the normal pattern of cells in the skin which have these receptors was found to be vastly different from the pattern found in patients without PPP, even smokers without PPP. The researchers think that “there is an abnormal response to nicotine in patients with PPP,” which could result in inflammation.[20]

Coincidentally, while examining the correlation between smoking and PPP, I ran across a study which says that patients with PPP sometimes experience a reduction in bone mineral density, which could lead to osteoporosis (the researchers also state that while four times as many PPP patients smoked as did their control patients without PPP, the amount of cigarettes smoked didn’t appear to have any effect on the reduction in bone mineral density).[21]

The Personal Touch

In what amounts to a very basic retroactive “poll” of psoriatics, I combed the Google archives of the psoriasis newsgroup to find out whether psoriatics themselves had any ideas about smoking and the disease, like whether or not quitting smoking would help eliminate psoriasis. After skimming perhaps 600 posts from the last seven years, I was able to fit 91 people into five broad categories:

1) Apparently good effects of quitting, or bad effects of starting: I figure if you quit smoking, and your psoriasis gets better, that’s about the same overall as if you start smoking, and either get psoriasis or your psoriasis flares up. Six of the eleven people in this category found their psoriasis got better after they stopped smoking. Three of them had flare-ups of the disease when they began smoking, and the last two had their first onset of psoriasis symptoms right around the time they began smoking.

2) Quitting makes psoriasis worse: Twelve of the fourteen people in this category reported that when they quit smoking, their psoriasis got worse. The first possibility that comes to mind is, of course, that the stress involved with quitting is what caused a flare-up, but this is really just speculative. The other two people in this category got their first psoriasis symptoms coincidental to quitting smoking.

3) Smoking (or not) makes no difference: The people in this category reported that there was either no apparent difference to their psoriasis between their smoking or non-smoking habits, or that they’d quit smoking, but were still using medications or other therapy to combat psoriasis. This is the biggest category, with 46 people in it.

4) People who’d quit smoking a long time prior to psoriasis showing up: These were people who’d quit well before psoriasis entered their lives. The closest anyone in this category came was four months between quitting and first symptoms. The longest was thirteen years. The average for all six people in this category was a little more than three years. While having smoked at one point in time may lead to an increased risk of psoriasis later in life, these six people can’t help answer the question of whether or not quitting smoking will lead to fewer psoriasis symptoms.

5) Other: Fourteen people found their way into this category, either because they’d started or quit smoking multiple times with different effects each time, or they quit or started smoking coincident to many other changes in their lives to make even a good guess as to whether or not it was the change in smoking habits that made for a change in their psoriasis symptoms. For example, a couple of people wound up in this category because they quit smoking by using Zyban, an antidepressant. Since psoriasis tends to be affected by things like stress, who’s to say whether it was the smoking cessation, or the antidepressant (or both) which made the psoriasis better?

It should be obvious at a glance that just about half of the people I could categorize fall into the “makes no difference” camp. The following table shows the numbers by percentage of people categorized:

1. Apparently good effects of quitting, or bad effects of starting12%
2. Quitting makes psoriasis worse15%
3. Smoking (or not) makes no difference51%
4. People who’d quit smoking a long time prior to psoriasis showing up7%
5. Other15%

Clearly, according to these numbers, once you’ve developed psoriasis, whether or not you smoke is rather unlikely to make a difference to the psoriasis symptoms themselves, since only 27% of the authors had any definite effects to report (categories 1 and 2). Of course, a few caveats should be noted: that the people in the above analysis were “self-selected” by the fact that they chose to speak up; that people tend to be fairly bad judges of how their own symptoms are increasing or decreasing; and that many of the newsgroup posts from which I culled the data were old, and the authors’ situations may have changed. Any of the these cautions about the numbers may be true for any of the five categories I used, though, so we can hope the proportions in each category were roughly equal.

Quitting Smoking

I can’t say it enough: regardless of what quitting smoking may (or may not) do to (or for) your skin, quitting smoking will probably do more to boost your overall health than anything else (if you smoke, that is — if you don’t, then don’t start). In other words, stopping smoking may not make your skin any better, but you’ll probably feel a lot better in general (at least, after the withdrawal symptoms go away).

If you’re planning on quitting, however, you might like to know that an Australian study found that use of nicotine patches in people with skin diseases resulted in slightly more “application site reactions” than in people with healthy skin.[22] In other words, if you’ve got psoriasis, and you use “the patch,” you might find that the skin under the patch reacts a little more angrily than other people might experience. Maybe.

Let me close by repeating, again, that whether or not cigarette smoking has any effects on psoriasis, it would probably be better if you quit smoking, or never start smoking. The health effects of smoking cigarettes are well-known and much more likely to do permanent harm than is psoriasis. Again, as Jerry J. said, “Quitting smoking is a far more important step toward future health than anything related to psoriasis.”

Reader Comments.



Note: I reference these papers for the information contained in their abstracts only. I am aware that the full-text articles may provide valuable additional information, but I am not able to access the full text for most of these as of this writing.

1.Alcohol intake: a risk factor for psoriasis in young and middle aged men?” Poikolainen et al, BMJ (Clinical Research Ed.) 1990 Mar 24;300(6727):780-3

2.Smoking habits in psoriasis: a case control study.” Mills et al, The British Journal of Dermatology 1992 Jul;127(1):18-21

3.Family history, smoking habits, alcohol consumption and risk of psoriasis.” Naldi et al, The British Journal of Dermatology 1992 Sep;127(3):212-7

4.Cigarette smoking is not a risk factor in atopic dermatitis.” Mills et al, International Journal of Dermatology 1994 Jan;33(1):33-4

5.Epidemiology of psoriasis: clinical issues.” Krueger and Duvic, The Journal of Investigative Dermatology 1994 Jun;102(6):14S-18S

6.A review of the epidemiology of psoriasis vulgaris in the community.” Plunkett and Marks, The Australasian Journal of Dermatology 1998 Nov;39(4):225-32

7. “[Psoriasis. Pathogenesis.]” Ortonne and Ortonne, La Presse Medicale 1999 Jun 26;28(23):1259-65

8.Excess mortality related to alcohol and smoking among hospital-treated patients with psoriasis.” Poikolainen et al, Archives of Dermatology 1999 Dec;135(12):1490-3

9.Pathophysiology and treatment of psoriasis.” Peters et al, American Journal of Health-System Pharmacy 2000 Apr 1;57(7):645-59; quiz 660-1

10.Cancer risk in a population-based cohort of patients hospitalized for psoriasis in Sweden.” Boffetta et al, The Journal of Investigative Dermatology 2001 Dec;117(6):1531-7

11.Mutagenic risk in psoriatic patients before and after 8-methoxypsoralen and long-wave ultraviolet radiation.” Sardas et al, Mutation Research 1994 Apr;312(2):79-83

12.Psoriatics in Norway. A questionnaire study on health status, contact with paramedical professions, and alcohol and tobacco consumption.” Braathen et al, Acta Dermato-Venereologica Supplementum 1989;142:9-12

13.Smoking, alcohol and life events related to psoriasis among women.” Poikolainen et al, The British Journal of Dermatology 1994 Apr;130(4):473-7

14.Association of early-stage psoriasis with smoking and male alcohol consumption: evidence from an Italian case-control study.” Naldi et al, Archives of Dermatology 1999 Dec;135(12):1479-84

15.Skin disorders in relation to oral contraception and other factors, including age, social class, smoking and body mass index. Findings in a large cohort study.” Vessey et al, The British Journal of Dermatology 2000 Oct;143(4):815-20

16.Pustulosis palmoplantaris and chronic eczematous hand dermatitis. Treatment, epidermal Langerhans cells and association with thyroid disease.” Rosén, Acta Dermato-Venereologica Supplementum 1988;137:1-52

17.The relationships of onset and exacerbation of pustulosis palmaris et plantaris to smoking and focal infections.” Akiyama et al, The Journal of Dermatology 1995 Dec;22(12):930-4

18.Risk factors for palmo-plantar pustulosis in a developing country.” Kubeyinje and Belagavi, East African Medical Journal 1997 Jan;74(1):54-5

19.Palmoplantar pustulosis: a clinical and immunohistological study.” Eriksson et al, The British Journal of Dermatology 1998 Mar;138(3):390-8

20.Expression of nicotinic receptors in the skin of patients with palmoplantar pustulosis.” Hagforsen et al, The British Journal of Dermatology 2002 Mar;146(3):383-91

21.Decreased bone mineral density in patients with pustulosis palmaris et plantaris.” Nymann et al, Dermatology (Basel, Switzerland) 1996;192(4):307-11

22.Predictors and timing of adverse experiences during trandsdermal nicotine therapy.” Gourlay et al, Drug Safety 1999 Jun;20(6):545-55