The CASM method

Blending different prescribed drugs into the base emollient cream is also known as CASM – combined antibacterial, steroid and moisturiser.

By diluting the steroid and antibacterial cream into the moisturiser, one can get the exact amounts right for each element according to formulas that doctors already use.

Doctors have tended to use a guide for the amount of moisturiser needed for the age and size, and fingertip units for steroid and antibiotic creams. Since two fingertip units equals 1g of cream, one can safely produce a blended cream knowing how much skin is needing treatment, the age, and the area affected.

The Aron method is safe and effective.

Compounded creams can contain more diluted steroids, with antibiotic, and emollient (moisturizer), and used for longer periods quite safely. The safety comes from diluting the steroid component well below that normally used, but still at effective dose. Moreover the effectiveness increases with frequent use during flares, and periodic once or twice weekly use between flares to increase time spent in remission, when staph can be kept in check, and the skin barrier function gradually repairs.

Although modern guidelines on management of atopic eczema discourage the over-use of antimicrobials in treating this condition CASM methods have been used now in South Africa, UK, Canada, USA, and Australia. Dermatologists have picked up this regime and evaluated it in patients who have previously been treated with mid or higher potency topical steroid creams or oral immune suppressives. Drs Lakhani, Lee and Lio, in Chicago demonstrated the benefit of his approach, showing the benefit of diluted steroid with antibacterial and moisturizer base, given at frequent intervals for the first few weeks, and tapering the frequency over time. They found it reduced the area affected by eczema and also the severity after just a few weeks.

Drs Totté, van der Feltz, Hennekam, Belkum, van Zuuren, and Pasmans, writing in the British Journal of Dermatology in 2016. They concluded that not only was Staph aureus colonising affected skin in flares of atopic dermatitis, but was also very commonly colonising unaffected skin, and the nose in such patients. They showed that staph aureus colonisation precedes a flare of atopic dermatitis, and releases alpha and delta toxins and then acts as a super-antigen, overcoming immune defences and increasing the inflammatory response in skin layers. They favoured the use of anti-staphylococcus antibacterial regimes. They noted that the more severe the eczema, the more likely clinicians were able to find Staph aureus colonisation. The pooled results from the 81 different clinical trials they reviewed, showed that 70% of patients with atopic dermatitis carried Staph aureus on affected skin. 39% of patients carried staph colonies on unaffected skin.

Drs Williams, Gibson, Aitchison, Lever and Mackie showed clearly in 1990 that increasing density of Staph aureus correlated with increasing severity of atopic eczema, and also that there was a reduced rate of the healthy bacteria, diptheroids. (British journal of Dermatology October 1990)

Dr Richard Williams, writing in the American Journal of Clinical Dermatology in 2000, concluded that antibiotics in combination with steroids produced a more rapid decrease in Staph aureus colonisation than topical steroids alone, but could not justify their use in mild atopic dermatitis.

In a multi-centre trial in China in 2006, Gong, Lin, Hao, Zemg, Bi, Yi, and Zhao demonstrated the superiority of a combined steroid antibiotic cream in patients with more severe atopic dermatitis, by the 7th day of treatment, and reduced rates of colonisation with staph aureus.

In the use of steroid based creams used twice weekly for prevention of flares, there is evidence for the benefit; Dr Elena Rubio-Gomis and colleagues from Valencia in Spain conducted a randomised controlled trial in 2018, showing that Cutivate (fluticasone propionate 0.05%) twice weekly reduced the risk of relapse in children with stabilized Atopic dermatitis. Average age was 5 years, and risk of relapse was more than halved.

The daily use of emollient creams once a day has been shown in multi-centre (USA and UK) randomised trials to reduce the risk of atopic dermatitis in susceptible children from the age of 3 weeks. Risk reduction is around 50% using daily emollients. Simpson, Chalmers et al, Journal of allergy and clinical immunology Oct 2014.

The implementation of treatment guidelines for atopic eczema is challenging, partly because there are different guidelines for different medical specialities, general practice, allergy and immunology, dermatology. (Boguniewicz, Fonacier, et al Annals of Allergy, Asthma and Immunology Jan 2018 p10-22) Therefore guidelines for atopic eczema are constantly changing.


Please contact me to learn more about my methods, or request an appointment if you are ready for a consultation.

The Aron method for treating eczema