What is Sorbitan Sesquioleate?
Sorbitan Sesquioleate (INCI: Sorbitan Sesquioleate; trade name: Arlacel 83; abbreviation: SSO) is a non-ionic emulsifier formed from sorbitan (a sugar alcohol derived from sorbitol) and oleic acid (a fatty acid). It is classified as a water-in-oil (W/O) emulsifier with a hydrophilic-lipophilic balance (HLB) value of approximately 3.7, making it useful in the formulation of thick, protective creams and ointments where the oil phase is continuous.
Sorbitan sesquioleate and related sorbitan esters (sorbitan oleate, sorbitan stearate) are widely used in pharmaceutical and cosmetic formulations. In pharmaceutical preparations, SSO appears in some medicated creams, corticosteroid preparations, and protective barrier ointments — contexts where it is specifically applied to compromised, inflamed, or eczematous skin.
Why does Sorbitan Sesquioleate cause reactions?
Sorbitan sesquioleate is an occasional contact allergen — its sensitization rate is low in the general population but becomes clinically significant in two situations:
- Application to compromised skin: Medicated creams containing SSO are specifically applied to inflamed or broken skin (eczema, psoriasis, dermatitis), where the disrupted barrier dramatically increases SSO penetration and sensitization potential
- Paradoxical worsening: A patient prescribed a corticosteroid cream for eczema, where the cream contains SSO, may develop contact allergy to SSO. The steroid provides some anti-inflammatory relief, but the SSO allergy prevents full healing — creating a picture of treatment-resistant eczema that improves only when the specific cream is changed
This is the "allergen-in-treatment" paradox that contact dermatologists specifically look for in patients with chronic, treatment-resistant eczema.
Where is Sorbitan Sesquioleate found in products?
- Pharmaceutical medicated creams and ointments: Corticosteroid creams, antifungal creams, and barrier preparations
- Some cosmetic moisturizers: Thick protective creams in W/O formulation
- Industrial emulsions: Some workplace skin protection creams
How to spot Sorbitan Sesquioleate on labels
- Sorbitan Sesquioleate — INCI name
- Arlacel 83 — trade name (appears in formulation databases, not usually on product labels)
In Indian products 🇮🇳
Sorbitan sesquioleate may be present in some Indian pharmaceutical topical preparations — cream-based products used for eczema, psoriasis, and other dermatological conditions. Indian patients using prescription medicated creams for chronic skin conditions who experience persistent or worsening reactions at the site of application should discuss the possibility of contact allergy to cream components, including SSO, with their dermatologist.
Patch testing for emulsifier allergens including SSO is available at contact dermatitis clinics in major Indian cities.
Safer alternatives
- Petrolatum (Vaseline)-based ointments: Contain no emulsifiers — pure petrolatum is one of the least allergenic vehicles available
- Emulsifier-free formulations: Some pharmaceutical companies offer emulsifier-free cream bases for patients with known emulsifier allergy
- Olive oil-based or light mineral oil vehicles: Alternative cream systems may be better tolerated