Objective: Studies have shown the relationship between vitamin D levels and many chronic diseases and skin diseases. The aim of this study was to investigate the relationship between vitamin D levels and commonly seen dermatological diseases like seborrheic dermatitis (SD) and telogen effluvium (TE).

Material and Method: As a result of history and dermatological examination, patients diagnosed with SD and TE were included in the patient group, and patients diagnosed only with TE were included in control group. Serum 25-OH vitamin D levels were measured in all patients.

Results: A total of 149 volunteers, 69 patients (SD and acute TE; n =42 and SD and chronic TE; n =27) and 80 controls (acute TE; n =69 and chronic TE; n =11) participated in the study. Serum 25-OH vitamin D level was 14.59±4.68 ng/mL in patients with acute TE, 16.86±7.31 ng in patients with chronic TE, 15.33±7.97 ng/mL in patients with SD and acute TE, 17.73±5.17 ng/mL in patients with SD and chronic TE. Serum 25-OH vitamin D level was significantly higher in patients with SD and chronic TE compared to patients with SD and acute TE (p <0.05). There was a medium strength significant positive correlation between SD and TE duration (r: 0.489) (p <0.001).

Conclusion: In this study, vitamin D deficiency was detected in all groups. It may be beneficial to evaluate vitamin D levels in SD and TE patients, and treat them when vitamin D levels are low.