UVB lighting is one of the most misunderstood parts of lizard care—and one of the most important. Incorrect UVB is a leading cause of serious health problems in pet lizards across the UK. This guide explains what UVB is, why it matters, and how to get it right, without the jargon.
What Is UVB and Why Do Lizards Need It?
UVB is a type of ultraviolet light that allows lizards to produce vitamin D3 in their skin. Vitamin D3 is essential for absorbing calcium from food.
Without UVB, lizards cannot use calcium properly—even if you supplement their diet.
What Happens If UVB Is Wrong or Missing?
Incorrect or missing UVB can lead to Metabolic Bone Disease (MBD), which causes:
- Soft or deformed bones
- Tremors and shaking
- Paralysis
- Painful movement
- Shortened lifespan
MBD is common, preventable, and often irreversible once advanced.
Do All Lizards Need UVB?
Most pet lizards do need UVB.
Common examples that require UVB:
- Bearded dragons
- Uromastyx
- Skinks
- Anoles
- Chameleons
Some nocturnal species (such as leopard geckos and crested geckos) can survive without UVB, but low-level UVB is still beneficial and increasingly recommended.
Tube vs Compact UVB Bulbs
This is where many beginners go wrong.
UVB Tube Bulbs (Recommended):
- Provide even UVB coverage
- Better for most enclosures
- Essential for larger lizards
Compact / Coil Bulbs:
- Limited UVB spread
- Only suitable for very small enclosures or temporary setups
- Often insufficient on their own
For most UK keepers, UVB tubes are the safest choice.
Choosing the Correct UVB Strength
UVB bulbs come in different strengths (often shown as percentages).
General guidance (species-dependent):
- Low UVB (5–6%) – Shade-dwelling species
- Medium UVB (10–12%) – Many common lizards
- High UVB (12–14%) – Desert species
Always match UVB strength to the species—not guess.
Distance & Placement Matter
UVB only works within a specific distance.
Key rules:
- Follow manufacturer distance guidelines
- UVB should overlap the basking area
- Mesh lids reduce UVB output
- UVB must not be blocked by glass or plastic
Incorrect placement can make good bulbs ineffective.
UVB Bulbs Must Be Replaced
UVB output fades over time—even if the bulb still lights up.
Typical replacement schedule:
- UVB tubes: every 6–12 months (check manufacturer guidance)
- Compacts: often sooner
Not replacing bulbs is a very common UK keeper mistake.
UVB Is Not a Replacement for Calcium
UVB and calcium work together.
You still need to:
- Dust food with calcium
- Use vitamins as advised
- Provide correct diet
UVB alone is not enough.
Common UVB Myths
- ❌ “My lizard is near a window” (glass blocks UVB)
- ❌ “The bulb still lights so it’s fine”
- ❌ “No UVB needed if I use supplements”
These myths cause serious harm.
UK Welfare Guidance
Animal welfare organisations such as the RSPCA highlight correct lighting as a key part of meeting reptiles’ welfare needs under UK care standards.
Final Thoughts
If you get one thing right for your lizard, make it UVB. Correct UVB lighting prevents painful disease, improves appetite and behaviour, and allows your lizard to live a full, healthy life.
If you’re unsure:
- Ask before buying
- Match UVB to species
- Replace bulbs on time
Getting UVB right isn’t complicated—it just needs to be done properly 🦎