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Head-to-head evidence comparison — which supplement is right for you?
Sunscreen (SPF) vs Urea: Sunscreen (SPF) has the stronger overall evidence (9 vs 6/10); the best pick depends on your goals. Take the 60-second quiz for a pick tailored to your goals.
Sunscreen (SPF) wins 2 of 3 categories. Both are solid choices — the best pick depends on your specific goals.
Verdict
Mostly mechanism / observational
Top outcomes
Verdict
Mostly mechanism / observational
Top outcomes
Shared outcomes (1)
Outcomes where both Sunscreen (SPF) and Urea have evidence — compare verdict strength side-by-side.
Topical OTC. Apply a broad-spectrum SPF 30+ sunscreen daily to sun-exposed skin as the last step of a morning routine, using an adequate amount (about 2 mg/cm² — roughly a nickel-sized dollop for the face, a shot-glass for the body) and reapply every ~2 hours of sun exposure and after swimming/sweating. Mineral (zinc oxide / titanium dioxide) filters are preferred if you're concerned about systemic absorption. There is no oral or systemic dose — it is not ingested. This library does not provide an ingestion protocol.
morning
Broad-spectrum SPF 30+, applied daily; mineral (zinc oxide/titanium dioxide) if concerned about absorption
Pick the concentration for the job: 5-10% for daily moisturising of dry skin, 20-25% for thickened skin and callus, 30-40% for nail softening or scale removal. Apply once or twice daily.
any
Urea 10% cream for daily dry skin
Throughout
Ongoing (years)
Ongoing
Throughout
immediate
2-4 weeks
1-2 weeks
4 weeks
Sunscreen and prevention of skin aging: a randomized trial.
Ann Intern Med (2013) · Rct · n=903
Randomized community trial (n=903): the daily sunscreen group showed no detectable increase in photoaging (skin microtopography) after 4.5 years
Molecular mechanisms of photoaging and its prevention by retinoic acid: ultraviolet irradiation induces MAP kinase signal transduction cascades that induce Ap-1-regulated matrix metalloproteinases that degrade human skin in vivo.
J Investig Dermatol Symp Proc (1998) · Review
Mechanistic model: UV activates MAP-kinase pathways and AP-1, which upregulate matrix metalloproteinases (MMPs)
Daily Use of a Facial Broad Spectrum Sunscreen Over One-Year Significantly Improves Clinical Evaluation of Photoaging.
Dermatol Surg (2016) · Open label · n=32
Single-arm prospective study (n=32): broad-spectrum SPF 30 applied daily to the face for 52 weeks
Effect of Urea Cream on Hand-Foot Syndrome in Patients Receiving Chemotherapy: A Meta-analysis
Cancer Nurs (2022) · Meta analysis · n=1387
Seven trials, 1387 patients, PROSPERO-registered. Both risk ratios below come from the prophylactic subgroup, not the whole pool.
Randomized controlled trial on the efficacy of topical urea-based cream in preventing capecitabine-associated hand-foot syndrome
BMC Cancer (2025) · Rct · n=216
THE COUNTER-EVIDENCE: a 216-patient randomised trial in which every prespecified endpoint was null.
Emollients and moisturisers for eczema
Cochrane Database Syst Rev (2017) · Meta analysis · n=6603
The Cochrane review that sets the context urea has to be judged in: 77 studies, 6603 participants.
Sunscreen (SPF) has a higher evidence score (9/10 vs 6/10) and wins in 2 of 3 categories.
No known interactions between Sunscreen (SPF) and Urea have been documented in our database. However, always consult a healthcare provider before combining supplements.
The right pick depends on your goals. Answer a few quick questions for a personalised recommendation — or dig into the full evidence on each.