Cinoxate Safety: An Obsolete Filter, an Empty File

Is Cinoxate Safe? The Short Answer

The honest answer is that nobody knows, and the reason is unusually well documented. Cinoxate is one of twelve UV filters the FDA proposed as Category III in its 2019 review: "The public record does not contain sufficient data to support a positive GRASE determination for cinoxate … at this time." The 2021 proposed order that replaced that rulemaking proposes requirements "substantively the same" as the 2019 rule and says its scientific discussions "are generally the same." Neither has been finalized, which is why cinoxate is still marketable.

Within that group, cinoxate is at the empty end of the scale. Of the ten filters with the largest data gaps, the FDA noted that only three — homosalate, octinoxate and octisalate — "appear to have been evaluated in human absorption studies." Cinoxate was not among the three. None of the ten has been through an adequate maximal-usage trial either.

Nor is there any sign of that gap being filled. When the FDA offered to defer a decision for ingredients whose makers were generating data, it received a request covering eight filters; cinoxate was not one of them.

What this does not mean is that cinoxate has been shown to be harmful. It means the question was never answered, and the ingredient became obsolete before anyone bothered. Practically, the decision makes itself: cinoxate is a weak UVB-only filter, so there is nothing to give up by choosing a sunscreen built on something better characterised.

Chemical Properties and UV Protection

Cinoxate is a cinnamate ester approved at up to 3% concentration in the US. Despite FDA approval, it's rarely used due to poor performance compared to modern filters. When found, it typically appears in lip balms or combination products rather than primary sun protection.

Inadequate UV Coverage

Cinoxate's protection profile is notably weak:

• Peak absorption at 289 nm (UVB only)
• No UVA protection whatsoever
• Minimal SPF contribution even at maximum concentration
• Requires multiple additional filters for basic protection

At maximum approved concentration (3%), cinoxate typically contributes only 1-2 SPF units, making it one of the weakest approved sunscreen ingredients.

Limited Safety Data

Available information suggests:

• Likely absorbed through skin (common for cinnamates)
• No FDA absorption studies conducted
• Unknown endocrine activity
• Limited allergic reaction data
• No environmental impact assessments

Photostability Concerns

Like other cinnamate esters, cinoxate may suffer from photodegradation:

• Breaks down under UV exposure
• Loses protective capacity over time
• May form unknown degradation products
• Requires frequent reapplication

Market Presence

Cinoxate's current usage is extremely limited:

• Rarely found in US products
• Not approved in EU, Australia, or Japan
• Occasionally in lip products for minimal UVB protection
• Sometimes in combination with other weak filters

Most manufacturers have replaced cinoxate with more effective modern filters that provide superior protection at lower concentrations.

Regulatory Status

United States: Approved at up to 3% concentration. FDA has not determined GRASE status due to insufficient data.

European Union: Not approved for use in cosmetics.

Other regions: Generally not approved or used internationally.

Comparison to Modern Filters

Cinoxate's obsolescence becomes clear when compared to current options:

Risk-Benefit Analysis

Minimal Benefits

• Extremely weak UV protection
• No unique formulation advantages
• Easily replaced by better filters

Unknown Risks

• Lack of safety data
• No absorption studies
• Unknown long-term effects
• Potential photodegradation products

Why It Persists in Approval

Cinoxate remains FDA-approved despite obsolescence due to:

1. Regulatory inertia: Grandfathered approval from 1978
2. Low priority: Minimal use means little pressure for review
3. Industry disinterest: Manufacturers have moved on
4. No safety signals: Limited use prevents adverse event reports

Recommendations

Given cinoxate's poor protection and data gaps:

• Avoid products containing cinoxate: Better options are widely available
• Check lip balms: Most likely product category to contain it
• Choose modern filters: Any other approved filter provides superior protection
• Question formulations using it: May indicate outdated or substandard products

Cinoxate represents the problem of outdated approvals persisting in regulations. While not demonstrably harmful, its weak protection and lack of safety data make it an poor choice when effective, well-studied alternatives exist. Consumers finding cinoxate in products should question whether the manufacturer is using current formulation practices. Its presence often signals a product that hasn't been updated in decades.

Recommended: Badger Mineral Sunscreen Face Stick SPF 35 — a cinoxate-free mineral alternative — uncoated zinc oxide in a face stick