Licorice extract proves helpful in hair removal

Frankfurt, Germany - A study using glycyrrhizic acid, the herbal extract from licorice, proves to be effective in halting hair growth in rats. This topical approach appears to be promising for future epilation therapies, and may rival currently used epilation modalities, which can frequently be associated with a host of unwanted side effects.

In the experiment, 15 percent glycyrrhizic acid was dissolved in an aqueous solution containing 10 percent urea and 20 percent ethanol at 80 degrees Celsius. The solution was cooled down to 40 degrees and topically applied to the back of the neck of Wistar rats twice a day for two weeks followed by four weeks without treatment for a total of two years. Histological analysis, scanning electron microscopy as well as in situ TUNEL assay were performed evaluating treatment outcomes.

Experiment outcome

Results showed that hair loss was visible as early as three days after the first treatment application of the solution, and after six to 12 days of treatment, the targeted skin was nearly free of hairs without any sign of skin irritation or other unwanted side effects.

The histology of the hair follicles and scanning electron microscopy of hairs showed damage to the anchoring structures of the hair cuticle and a detachment of the hair shaft from the follicular wall. Also, the in situ TUNEL assay showed apoptotic cells in the bulge region after treatment with glycyrrhizic acid.

“Though we noticed that the hairs began to grow again after each treatment, the hair shafts were thinner, the hair density per skin area was decreased and we were able to achieve a permanent reduction in re-growing hair quantity by more than 50 percent,” says August Bernd, Ph.D., professor of the department of dermatology and venerology, University Hospital, J. W. Goethe University, Frankfurt/Main, Germany, and co-author of the study. “Even after a periodically long-term treatment for the one year we evaluated, we did not see any abnormalities of the skin surface at the target areas nor any dysplastic changes in the histology.”

Glycyrrhizic acid is an herbal extract commonly used in traditional Asian medicine and appears to be responsible for the epilatory effect seen. Liqorice has a known anti-androgenic effect and inhibits alpha five reductase and androgen receptors.

Potential for treatment

The topical treatment with glycyrrhizic acid shows much promise as a quick, safe and effective method for hair removal and, according to Dr. Bernd, there do not appear to be any disadvantages with this therapy. The underlying mechanism of action of glycyrrhizic acid on hair removal is still unknown and clinical trials are the next step, Dr. Bernd says.

“Current hair removal approaches such as topical creams and laser treatments are variably effective and can be associated with a slew of unwanted side effects, including pain, skin irritation, contact eczema, folliculitis and hyperpigmentation.

“The topical treatment with glycyrrhizic acid showed to be effective in achieving a quick and painless method for hair removal and glycyrrhizic acid is at least a candidate molecule for the development of a new promising epilating drug which very well may rival currently used hair removal approaches,” Dr. Bernd says.

Disclosures: At the beginning of the study Dr. Bernd and his colleagues received some support from the German Academic Exchange Service, but later financed the study with their own budget.