A new treatment for the flushing and redness of rosacea?

No one really knows what triggers the signs and symptoms of acne rosacea; it is hypothesised that some of the problems of rosacea are due to a ‘neuron-mediated’ vascular dysfunction which means that nerves in the skin effect how much blood flows into the skin by acting directly on blood vessels. Neurotoxin works by blocking the release of acetylcholine which is one of the neurotransmitters that signals changes in blood vessel diameter.

Based on this, the use of neurotoxin is a suggested approach for the management of erythematotelangiectatic rosacea. Instead of injecting into the muscle as would be the technique for treating wrinkles, for redness the neurotoxin is injected intradermally (into the dermis) and in very small quantities, in order to minimise the risk of it affecting the underlying muscles. The claimed effects of these ‘micro’ injections into, for example, the cheek area, include a reduction in oil production, decreased papules and pustules, reduced flushing in the treated area and an overall reduction in facial redness. (Neurotoxin potentially also blocks the activity of ACH on sebocytes)

There have been two randomised placebo-controlled trials of the use of neurotoxin in the treatment of the redness of rosacea. Both studies used a split face design where half the face got neurotoxin injections and the other half just normal saline (salt water).

Oh et al (2011) treated 15 Korean subjects who complained of facial flushing and they found no difference in improvement in facial redness between the different sides of the face. In 2019, Kim et al performed a split-face design in 24 also Korean patients with facial flushing. They found that the neurotoxin treated side showed a significant decrease in redness compared to the vehicle side.

They used a more detailed quantitative method to collect data about changes seen. Kim et al injected 15 units of neurotoxin into the cheek area only while Oh et al injected roughly the same amount into the entire half of the face. Could this account for the difference in results?

Though these studies have pretty decent methodology and statistical analysis, they both only have a small number of subjects which makes it hard to draw any meaningful conclusions. The verdict is still out on whether or not neurotoxin can be safe and effective for the treatment of facial redness and flushing.