Rosacea

In Germany, medicinal products with metronidazole (0.75%) in the form of gel, cream, lotion and microemulsion, azelaic acid gel (15%), brimonidine gel (0.33%) and ivermectin cream (1%) are approved for external rosacea treatment. The most commonly used is metronidazole, which has antibiotic and antiparasitic activity. The effect mechanism with topical application is not yet fully understood. Since skin parasites such as demodex mites are involved in the pathogenesis of rosacea, the antiparasitic effect could play a role. Unwanted effects are rare and usually manifest as local hypersensitivity reactions with symptoms such as redness, burning and dehydration. Ivermectin cream is also effective against the parasites. Unlike metronidazole preparations, the cream is only applied once a day. Azelaic acid has an antibacterial and anti-inflammatory effect and normalises the keratinisation of the skin. The gel is applied twice a day. The topical vasoconstrictor brimonidine is indicated for symptomatic treatment only when persistent erythema occurs. According to the guideline, doctors can use other topicals such as minocycline, permethrin or clindamycin, topical retinoids, calcineurin inhibitors or benzoyl peroxide as part of an off-label use. Once the acute episode is over, treatment moves to maintenance therapy. Topical metronidazole preparations, brimonidine gel and ivermectin cream are suitable for this.

For severe and therapy-resistant forms, the authors of the guideline recommend systemic therapy. Doctors often prescribe doxycycline and, as an alternative, minocycline. In cases of intolerance to tetracyclines, therapy resistance or contraindications such as pregnancy, macrolides such as erythromycin, clarithromycin and azithromycin are available.

Although there is evidence from studies that cotrimoxazole, clindamycin, chloramphenicol and ampicillin are also effective, experience with these antibiotics is limited. The guideline authors continue to recommend low-dose isotretinoin and the beta-blocker carvedilol as systemic therapy. Glucocorticoids, on the other hand, can worsen the disease and trigger steroid rosacea. The only exception, according to the guideline, is short-term use for rosacea fulminans. There is evidence that oral rifaximin may help in rosacea. The non-absorbable broad-spectrum antibiotic acts locally in the intestine and has been approved in Germany since 2008 for the treatment of travellers' diarrhoea in adults. Rifaximin seems to counteract a faulty colonisation of the small intestine, which is common in rosacea and whose role in the disease process is unclear. Treatment-resistant patients can be offered laser therapy or therapy with an intense pulsed light source (IPL). In the case of a bulbous nose, ablative laser therapy with CO2 laser or Er:YAG laser is an alternative to surgical correction. In individual cases, photodynamic therapy (PDT) can improve rosacea.