Sulfur (spelled sulpher in Europe) is a yellow, non-metallic natural element and one of the building blocks of life. Sulfur is present in many proteins, vitamins and hormones that are necessary for a healthy skin. Sulfur is also a major component of keratin present in the skin, hairs and nails.

Because of its antifungal, antibacterial and keratolytic properties, sulfur has been for a long time a well known traditional medication for treating many skin problems including acne. It is also a good exfoliant for removing dead cells from the skin surface and helps to control oil production. Faced with competition from other medications the use of sulfur as a therapeutic agent in the treatment of acne has lately come down. However, its efficacy and safety has been well established and it still remains a good and reliable treatment option.

Mechanism of action

Sulfur is used alone and also in combination with compounds such as sodium sulfacetamide and salicylic acid for treating acne. How sulfur works as a medication is not well known. It is believed that when sulfur is applied to the skin it reacts with a substance called cysteine present in the skin and produces hydrogen sulfide. Hydrogen sulfide breaks down keratin, resulting in a process called keratolytic activity. The application of sulfur on the skin also produces pentathonic acid which is toxic to fungus giving sulfur its antifungal property. Its bacterial property is demonstrated by the fact that sulfur has an inhibitory effect on propionibacterium acne.

Sulfur

A study was done to compare the effectiveness of sulfur 10% cream with systemic tetracycline. At the end of the study the only difference found was in the number of papules and pustules. The sulfur cream achieved a greater reduction in the number of inflamed lesions. Also there was no difference in the relapse rate within 6 months.
Compared to other medications such as oral antibiotics, tretinoins, antimicrobials and retinoids, sulfur produces very mild side effects at the application site.

Sulfur is well absorbed by the body system. This was well demonstrated in a study where sulfur was detected in the epidermis two hours and throughout the skin within eight hours of application. Twenty four hours after application no sulfur could be detected in the skin. Such systemic absorption was demonstrated when 25% sulfur ointment was applied to abraded animal skin. However, no such absorption took place when sulfur was applied to healthy animal skin.

Earlier studies had reported that sulfur was comedogenic on rabbit ears and the human back. This issue was reexamined recently in a study which involved application of a 5% test solutions of sulfur on comedone free skins of healthy subjects with or without acne. These applications were made three times per week for six weeks. At the end of the study it was found that there was no correlation between comedone developments and the presence or absence of sulfur in the formulation applied.

Sulfur with sodium sulfacetamide

Sodium sulfacetamide has antibacterial properties. It inhibits the action of paraaminobenzoic acid which causes bacterial growth. It is also effective in suppressing the growth of propionibacterium acne. What makes sodium sulfacetamide particularly attractive is its effectiveness combined with the absence of any major side effects. The response to treatment is consistent and it’s cosmetically appealing formulation gets long term compliance of the patient.

The combination of sulfur and sodium sulfacetamide has been shown as an effective therapy for acne lesions without excessive erythema. Clinical trials, conducted with sulfur 5% and sodium sulfacetamide 10% formulations, were found to be quite effective in reducing the number of comedones and inflammatory lesions. Almost 70 to 80% reduction was observed for both total number of lesions and the inflamed lesions. The side effects such as dryness and itching were rare, short lived and mild.

Formulations of sulfur and sodium sulfacetamide are available as lotions, topical suspensions and cleansers.

Conclusions

The efficacy of sulfur therapy compared to other treatments is well established. From the point of view of safety, considering its mild and very transient side effects, it should undoubtedly be a preferred treatment in many cases. Although the use of sulfur and its compounds in acne treatment has declined, it still remains a good treatment option.