Kalaf (melasma), also called chloasma, is a chronic acquired hyperpigmentation characterized by irregular brown macules and patches, symmetrically distributed on sun exposed areas of face and less frequently the forearms[1,2]. It mainly affects women during childbearing years with age of onset 30-38 years and approximately 4 :1 female to male ratio in India[3] while 8:1 female to male ratio also reported from south India[4]. It has a deleterious impact on quality of life[5]. The prevalence of melasma determined by various epidemiological studies varies between 1% in general population and 9% to 50% in higher risk population like in pregnancy[6]. 

The etiology of melasma is multifactorial which includes genetic influences, ultraviolet (UV) radiation, pregnancy, hormonal therapies, cosmetics, phototoxic drugs, and antiseizure medications[6,7]. Mostly, prolonged UV exposure-induced dermal inflammation and fibroblast activation upregulate stem cell factors in the melasma dermis, resulting in increased melanogenesis[7]. Histologically, it is classified as epidermal (most common ~70%), dermal and mixed[8], although some authors classified it as epidermal and mixed only[9].

In conventional medicine, melasma is treated mainly by topical therapies which includes hydroquinone alone or triple combination (hydroquinone, tretinoin, and corticosteroid). Beside this, chemical peels, laser- and light-based devices, and oral agents are also used. Among these, hydroquinone monotherapy and triple combination cream are the most effective and well-studied treatments for melasma, whereas other therapies are equal or inferior to topicals [5,7]. 

All these treatment including hydroquinone has reported adverse events such as skin irritation, dryness, burning, erythema, and post-inflammatory hyperpigmentation[5] which creates a potential space to search for alternative safe, effective and economical treatment for melasma. 

The description of melasma can be found extending as far as the reports of Hippocrates (470-360 BC). Even the term melasma originates from the Greek word "melas", which means black. The term was used to identify a series of cutaneous melanization processes, and its worsening was reported to happen after sun exposure, fire heat, cold and skin inflammations[2].  The Unani system of medicine is based on the principles of Hippocrates and melasma is described extensively in classical Unani literature with Arabic translated term Kalaf.

Unani scholars have described it as a blackish discoloration of the skin in the form of patches or spots. The main cause suggested by Ibn Sina and Majūsi is Fasād-i Dam (derangement of sanguine) or Dam -i Muḥarraq (burnt sanguine) which results in Ghalba-i Sawda’ (predominance of black bile). Moreover, Sawdāwi Bukhārāt (melancholic vapours), excessive intake of Muwallid-i Sawda’Aghziya (black bile producing diet), Du’f-i Tihāl (weakness of spleen) and Ihtibās-i Tams (amenorrhoea) can also responsible for the development of Kalaf (melasma)[10–13].

The line of treatment is based on Istifrāgh-i Sawda’ (evacuation of black bile) followed by Tasfiya-i Jild through Jāli Adwiya (detergent drugs). For the purpose a number of single and compound drugs are recommended by Unani scholars. 

Among all those recommendations, Tukhm-i Turb (Rhaphanus sativus) with ‘Asl (honey) is widely described in Unani literature as an effective and potent medicine for melasma which possesses Jāli (detergent) action which helps to reduce hyper melanosis[10–14]. It is also reported that Raphanus sativus contains vitamin C, pelargodinin-3-sophoroside-5-glucoside and caffeic acid. Also, it exhibits anti oxidative, antitumour, antiviral and cardioprotective activities[15].

Keeping all the facts in consideration, present study is designed to evaluate the safety and efficacy of Tukhm-i Turb (Rhaphanus sativus) and honey as a vehicle in the management of Kalaf (melasma) titled “Therapeutic evaluation of topical Tukhm-i Turb (Raphanus sativus) in Kalaf (melasma) - a randomised control trial”.