**10. Alcoholic beverages**

The first studies on the association between psoriasis and the consumption of alcoholic beverages emerged in 1963. While some investigations have failed to demonstrate such an association, recent studies have shown a significant correlation (Wolf et al., 1999). Besides contributing to the development of psoriatic plaque, alcohol intake is involved in triggering periods of exacerbation, associated with a reduced response to treatment and the risk of liver toxicity associated to the use of methotrexate (Gupta et al., 1993; Higgins et al., 1994; Liu et al., 2010; Qureshi et al., 2010; Smith & Fenske, 2000).

The exact mechanism by which alcohol causes or aggravates psoriasis is not yet fully clarified. Some authors propose that alcohol induces immunological dysfunction, leading to immunosuppression, and increases the production of inflammatory cytokines and cell cycle activators, such as cyclin D1 and keratinocyte growth factor, which could lead to epidermal over-proliferation (Farkas et al., 2003; Ockenfels et al., 1996; Smith & Fenske, 2000). Moreover, the greater susceptibility to superficial infection observed in alcoholics, such as those caused by Streptococcus and trauma, has also been suggested in the development of psoriasis (Farkas et al., 2003).

Data from literature indicates that alcohol is a risk factor for psoriasis in young and middleaged men and, while not a risk factor in women, alcohol intake aggravates the condition in this gender (Poikolainen et al., 1994). Patients with psoriasis are recommended to exercise with caution when consuming alcohol, especially during periods of exacerbation. Moreover, due to all possible effects, a number of authors recommend abstention (Behnam et al., 2005; Wolters, 2005). Thus, identifying this risk factor in patients with psoriasis could contribute toward a reduction in episodes of exacerbation, thereby achieving better treatment results (Kazakevich et al., 2011).
