Herbal Nanoemulgels for Topical Delivery: A Critical Review of Standardization, Quality by Design

Background: Herbal extracts, essential oils and pure phytochemicals are widely used on the skin, but poor solubility, volatility and weak penetration limit ordinary gels and creams. Nanoemulgels, which place a nanoemulsion in a gel base, have been proposed as a better vehicle. Objective: This narrative critical review appraises herbal nanoemulgels for topical delivery, from raw-material standardization and Quality by Design (QbD) to skin-delivery mechanisms, therapeutic evidence, safety, stability and translation. Methods: Fifty-five supplied sources (17 reviews, 38 primary studies) were checked through PubMed and judged with a structured checklist; 32 primary studies were read in full. No systematic database search was run. Evidence themes: Efficacy data came mainly from in vitro, ex vivo and small rodent studies. Chemical analysis of the herbal material, formal QbD tools, vehicle-only controls and sensitization tests were reported unevenly or not at all. Gaps: Human studies, scale-up work and regulatory pathways are largely missing. Conclusion: Herbal nanoemulgels look promising but remain preclinical. A staged roadmap, from standardized inputs to controlled human studies, is proposed.