Vitamin A and Leopard Geckos: Preformed vs Beta-Carotene
| Safer source | Beta-carotene |
| Riskier source (accumulates) | Preformed vitamin A / retinol |
| Check | Supplement ingredient label |
Two different forms of vitamin A
Preformed vitamin A (retinol) is used directly by the body with no internal regulation, while beta-carotene is a precursor the body converts to vitamin A only as needed. This distinction matters a lot for supplement safety.
Why preformed A is risky
Because preformed vitamin A isn't self-regulated, repeated dosing through a multivitamin that uses it can accumulate over time and cause hypervitaminosis A — symptoms include skin issues, lethargy, and, in severe cases, organ damage.
Why beta-carotene is safer
A gecko's body only converts the beta-carotene it actually needs into active vitamin A and excretes the rest, making toxicity from a beta-carotene-based multivitamin far less likely with normal use.
What to check on the label
Look at a supplement's ingredient list for 'vitamin A' or 'retinol' or 'retinyl' listed as the source versus 'beta-carotene.' Repashy Calcium Plus and several other well-regarded reptile multivitamins use beta-carotene specifically for this reason.
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A single adult leopard gecko needs a 20-gallon long tank as an absolute minimum, with a 36x18 in (40-gallon breeder) footprint now considered the recommended standard — plus a secure lid, an under-tank heater on a thermostat, a thermal gradient, at least three hides, and a shallow water dish.
Set up in this order: substrate, then heat source wired through a thermostat, then hides and water dish, then decor — and run the whole enclosure for at least 24–48 hours to confirm stable temperatures before your gecko moves in.
Hatchlings can start in a 10-gallon tank or tub, juveniles do well in 20 gallons, and adults need a 20-gallon long as an absolute minimum — with 36x18 in (40-gallon breeder) now the widely recommended standard, not just an upgrade.
Heat a leopard gecko enclosure with an under-tank heater and/or overhead heat source (halogen or deep heat projector) wired through a thermostat — a thermostat is mandatory, not optional, and heat rocks should never be used.
Leopard geckos can survive without UVB using dietary D3 supplementation, but current husbandry guidance now recommends low-level UVB (roughly 2–6% T5) as best practice — it improves D3 synthesis, bone density, and natural behavior, and views on it have shifted significantly from older nocturnal-species advice.
Keep ambient humidity around 30–40% across most of the enclosure, with a dedicated humid hide raised to roughly 70–80% to support smooth, complete sheds.