Canthaxanthin Retinopathy and the Evolution of Carotenoid Supplement Safety in Dermatology and Ophthalmology

Oral carotenoids have gained widespread popularity in both dermatologic and wellness markets for their perceived benefits in enhancing skin tone, promoting a “sun-kissed” appearance, and providing systemic photoprotection. Among these, compounds such as astaxanthin have emerged as promising agents due to their potent antioxidant, anti-inflammatory, and vascular-protective properties. However, the commercial enthusiasm for carotenoids is not without precedent and caution. Canthaxanthin, once marketed as a skin bronzing agent, was associated with crystalline retinopathy characterized by the deposition of birefringent crystals in the inner retina. Though often asymptomatic, this retinal toxicity raised substantial safety concerns, prompting regulatory restrictions and reformulations. This systematic review synthesizes clinical, imaging, and histopathologic data on canthaxanthin retinopathy, including its anatomical distribution, potential for visual field impairment, and long-term reversibility. We analyze case series, longitudinal follow-up studies, and tissue analyses to elucidate the pathophysiology and risk thresholds for ocular injury. In contrast, emerging data on astaxanthin and β-carotene suggest a more favorable ocular safety profile, with no reported cases of crystalline maculopathy despite widespread use in both supplement and clinical settings. The shift from canthaxanthin to alternative carotenoids highlights a broader trend in nutraceutical evolution where marketing potential often precedes rigorous safety assessment. As newer carotenoid formulations enter the market under the guise of wellness, dermatologic benefit, or photoprotection, this review underscores the critical need for long-term ocular surveillance, regulatory oversight, and evidence-based adoption.