Psoriasis is a chronic autoimmune disease that affects 1–3% of the population. The pathomechanism of psoriasis development is complex, but genetic (non-modifiable) factors play a key role. However, the importance of environmental factors and lifestyle choices, such as the diet, alcohol consumption, and smoking, is increasing. The objective of this review was to analyse the influence of dietary habits, alcohol consumption, and smoking on the clinical course of psoriasis. Stress, a poor diet, alcohol abuse, and smoking can trigger psoriasis or cause its exacerbation. Therefore, in addition to the correct selection of therapy, it is extremely important to educate patients about the impact of these factors on the onset and progression of psoriasis. This literature review confirms that a holistic and multidisciplinary approach is required for patients with psoriasis, further emphasizing Hippocrates’ thesis, “Let food be thy medicine, and medicine be thy food”.