What the Research Revealed
Some social media claims about sunscreen are partly based on scientific investigation. In 2019 and 2020, JAMA (Journal of the American Medical Association) published studies examining whether specific chemical sunscreen ingredients could be absorbed into the skin and subsequently detected in the bloodstream. Snopes had previously looked into a similar assertion concerning sunscreen chemicals and blood absorption, concluding that absorption alone doesn’t automatically signify risk.
The 2019 JAMA study evaluated four sunscreen ingredients—avobenzone, oxybenzone, octocrylene, and ecamsule—under conditions described by researchers as “maximal use.” The findings indicated that all four ingredients were absorbed into the bloodstream.
The subsequent 2020 JAMA study involved 48 healthy adults and tested four sunscreen products. Researchers analyzed six active ingredients: avobenzone, oxybenzone, octocrylene, homosalate, octisalate, and octinoxate. Under the study’s parameters, all six ingredients were detectable in participants’ blood after sunscreen application. Levels for all six surpassed 0.5 nanograms per milliliter, a threshold the FDA uses to determine if further safety testing is necessary. This occurred after a single application on the first day of the study.
These findings support the limited conclusion that certain sunscreen ingredients can enter the bloodstream within 24 hours. However, the 0.5 ng/mL figure was not presented as a “danger line,” and the study did not establish that these ingredients cause cancer or any other disease. The researchers emphasized the need for more investigation, and the study itself noted: “These findings do not indicate that individuals should refrain from the use of sunscreen.”
FDA’s Position
The FDA has acknowledged that some sunscreen ingredients can be absorbed through the skin and enter the body. However, the agency has not stated that absorption in itself renders these ingredients unsafe.
During an FDA discussion on sunscreen in 2020, Terri Michele, then director of the FDA’s Division of Nonprescription Drug Products, stated that the absorption of an ingredient through the skin and into the body “does not mean that the ingredient is necessarily unsafe.” She indicated that these findings warranted further safety testing for repeated use but advised the public to continue using broad-spectrum sunscreens with SPF 15 or higher, along with other sun protection methods.
The FDA has indicated that zinc oxide and titanium dioxide possess sufficient safety data to be considered “generally recognized as safe and effective” (GRASE). For several other active sunscreen ingredients, including avobenzone, oxybenzone, octocrylene, homosalate, octisalate, and octinoxate, the FDA stated that additional data is required. Importantly, the agency also clarified that this request for more data does not imply that these ingredients have been found to be unsafe.
Vitamin D Considerations
Some social media discussions have also suggested that sunscreen increases cancer risk by hindering vitamin D production. While sunscreen can reduce exposure to UVB radiation, which aids vitamin D synthesis, health organizations do not endorse intentional unprotected sun exposure as a cancer prevention strategy.
The American Academy of Dermatology states that there is no safe level of UV exposure from the sun or indoor tanning that allows for optimal vitamin D production without increasing skin cancer risk. They recommend obtaining vitamin D through diet and supplements.
In response to the assertion that sunscreen blocks vitamin D and thus “removes” the body’s cancer defenses, the academy informed Snopes via email: “There is no strong evidence supporting the claim that sunscreen blocks vitamin D and removes the body’s cancer defenses.” They added that making health decisions based on poorly substantiated evidence carries risks.
A 2019 review published in the British Journal of Dermatology also found that regular sunscreen use for daily and recreational sun protection generally does not compromise vitamin D synthesis, even when applied under ideal conditions.
The National Cancer Institute reports that research on vitamin D and cancer has yielded mixed results. They also advise individuals against attempting to boost vitamin D levels through increased sun exposure due to the elevated risk of skin cancer.
Public Health Guidance on Sunscreen
Public health recommendations have remained consistent despite the JAMA absorption studies. The Centers for Disease Control and Prevention emphasizes that most skin cancers are caused by excessive exposure to ultraviolet light. The FDA advises that broad-spectrum sunscreens with SPF 15 or higher can mitigate the risks of sunburn, skin cancer, and premature skin aging when used as directed alongside other sun protection measures.
The American Academy of Dermatology recommends a comprehensive sun protection plan: “seeking shade, wearing protective clothing, and applying a broad-spectrum, water-resistant sunscreen with an SPF of 30 or higher to all skin not covered by clothing.”
The American Academy of Dermatology also states that current scientific evidence does not indicate that any sunscreen ingredients currently available in the U.S. are harmful to human health. Similarly, a 2025 explainer from Stanford Medicine indicated that scientific studies have consistently demonstrated that regular sunscreen use reduces the incidence of skin cancer and slows the aging process.
Conclusion
It is true that some chemical sunscreen ingredients can be absorbed into the bloodstream. Studies by FDA researchers did find that six active ingredients exceeded a threshold used to determine the need for additional safety evaluations.
However, the claims circulating on social media extend beyond the available evidence. The JAMA studies did not establish that sunscreen causes cancer, nor did the FDA assert that sunscreen negates the body’s defenses. The American Academy of Dermatology stated that there is no evidence linking sunscreen use to cancer and no strong evidence that sunscreen significantly blocks vitamin D in a way that compromises the body’s cancer defenses.
Health authorities continue to endorse sunscreen as a crucial component of a broader sun protection strategy, which includes seeking shade, wearing protective clothing, and limiting excessive UV exposure.