Rayon is a popular textile fiber described as semi-synthetic, meaning it is derived from a natural source, typically wood pulp, but requires extensive chemical processing. The cellulose is chemically regenerated into a usable fiber. This combination of natural origin and chemical modification leads people to question if the fabric or the substances used to create it can trigger adverse skin reactions. The central issue is determining if irritation is a direct allergy to the fiber or a reaction to residual chemicals in the finished garment.
The Composition and Processing of Rayon
Rayon is classified as a regenerated cellulose fiber because wood pulp undergoes a transformation that alters its molecular structure before solidifying back into a fiber. The most common manufacturing technique is the viscose process, which requires dissolving the cellulose with strong chemicals, including sodium hydroxide and carbon disulfide. This viscous solution is then extruded through a spinneret into an acid bath, regenerating the cellulose into filaments suitable for weaving.
Although the final fiber is nearly pure cellulose, the use of highly reactive solvents introduces the possibility of residual chemicals. Trace amounts can persist in the finished textile despite washing efforts. Additionally, the fabric undergoes further chemical treatments after weaving, increasing the potential for skin irritants.
True Allergy Versus Contact Dermatitis
A true allergy to the rayon fiber itself—an immunological response to the regenerated cellulose—is extremely rare. Textile allergies are typically classified as Type I (immediate) or Type IV (delayed) hypersensitivity. Reactions seen with rayon are nearly always a form of contact dermatitis, which is localized skin inflammation.
Contact dermatitis has two types: Irritant Contact Dermatitis (ICD) and Allergic Contact Dermatitis (ACD). ICD is a non-immunological reaction caused by abrasive fibers or irritating chemicals, often exacerbated by sweat or friction. ACD is a delayed Type IV hypersensitivity reaction where the immune system recognizes a residual chemical as a threat, triggering inflammation upon re-exposure. Most skin reactions linked to rayon are ACD, caused by chemicals added during or after processing.
Identifying Symptoms and Common Chemical Triggers
Textile contact dermatitis typically presents as an eczematous rash characterized by redness, intense itching, and scaling. This rash often appears in areas where the fabric is in close contact with the skin, such as the armpits, groin, and upper back, especially where clothing fits tightly or friction occurs. Since Allergic Contact Dermatitis (ACD) is a delayed reaction, symptoms may not appear for several hours or days after exposure.
The primary culprits causing ACD in rayon clothing are chemical additives used to provide desirable textile qualities. Formaldehyde resins are the most common trigger, applied to make fabrics wrinkle-resistant, stain-repellent, or colorfast. Textile dyes, particularly disperse dyes, also represent a significant source of allergens that can rub off onto the skin, especially from dark-colored clothing.
Diagnosis, Treatment, and Prevention
Diagnosing textile contact dermatitis requires a dermatologist to identify the specific chemical responsible using patch testing. This procedure involves applying small quantities of common textile allergens, such as formaldehyde resins and dye mixes, to the skin under patches. The site is assessed for a delayed immune response after a couple of days. The patch test pinpoints the chemical additive the individual is sensitive to.
Treatment for an existing rash focuses on reducing inflammation and relieving intense itching. This is managed with topical corticosteroids, which decrease the immune response, and bland emollients to restore the skin barrier. Prevention involves avoiding the specific allergen identified by the patch test. Individuals can minimize exposure by seeking “formaldehyde-free” garments or by rigorously washing new rayon clothing to leach out residual chemicals and excess dyes.