Doxycycline is a synthetic tetracycline that was approved in 1967. This wide-spectrum antibiotic has been shown to also have useful anti-inflammatory properties that make it suitable for the treatment of a number of noninfectious conditions. Tetracyclines are probably the most commonly prescribed antibiotics in dermatology, where they are usually used at doses lower than those effective against infections. They also have an excellent efficacy and safety profile. Because of doxycycline's ability to inhibit the molecular pathways associated with certain processes, this antibiotic can be used to treat hair follicle diseases, granulomatous diseases, and vascular proliferation, among other conditions. The main properties of doxycycline and its many applications in dermatology make this drug one that specialists should become familiar with.

Atopic dermatitis (AD) is one of the most prevalent chronic inflammatory diseases. Head and neck (H&N) involvement, also known as the picture-frame pattern, can be a diagnostic and even therapeutic challenge. Sensitization to the fungus Malassezia furfur seems to be implicated in this clinical presentation. To investigate the role of Malassezia furfur in H&N dermatitis, we performed an observational single-centre study. Serum-specific IgE levels for Malassezia furfur were determined in a total of 25 patients with AD (15 receiving dupilumab treatment, 10 not receiving dupilumab), 14 patients with seborrheic dermatitis, and 19 healthy controls. Reactivity to Malasseziafurfur, in terms of serum-specific IgE levels (>0.35 Ku.arb./L), was found in 80% of patients with AD. Risk factors to consider include high total IgE levels, sensitization to multiple pneumoallergens, and elevated LDH and CRP levels. Prescription of topical antifungals, oral antifungals, or a combination of both showed good response in 100% of cases in the H&N AD group treated with dupilumab. The most appropriate treatment seems to be the use of oral itraconazole and/or ketoconazole cream. The median treatment time was 3 weeks. Localized dermatitis in H&N significantly affects the patient’s life. We present a study of sensitization to Malassezia furfur in patients with H&N AD. It is important to know the differential diagnosis and to approach the study correctly. Sensitization to Malassezia furfur may be one of the main reasons, especially in patients being treated with dupilumab. The use of antifungals allows for adequate control, avoiding treatment changes and improving the patient’s quality of life.