Nappy Rash Worries? CastorBub Is Here For Your Baby’s Delicate Skin

September 29, 2025 Tracey Bailey

I know when my girls were babies, I didn't want to lather them up with harsh chemicals, but I also wanted something that actually worked to keep them comfortable, and not crying out from the sting of nappy rash. For 20 years at Biome, we've been strong supporters of Australian-made natural bottom balms, and now we have created our own special solution — meet CastorBub.

When nappy rash strikes, it can get bad fast. What starts as a little redness can quickly turn into sore, inflamed skin that leaves babies distressed through nappy changes and during the night. That’s why prevention is so important — keeping a protective barrier on the skin helps stop rash before it takes hold.

If you're navigating baby essentials more broadly, our non-toxic baby essentials guide is a helpful place to start.

Common concerns parents have about baby creams

Chemical overload. A recent survey found that 90% of parents worry about toxic chemicals in baby products (Cosmetics Design Europe, 2024). And for good reason: many mainstream creams contain petroleum, silicones, parabens, and synthetic fragrance. Parents want something cleaner and safer.
Does it actually work? Nappy rash is one of the top frustrations in baby care. Some creams only treat the rash after it appears, while others can leave skin feeling dry. Parents want prevention too — a cream that forms a shield before irritation sets in.
Baby-soft skin is extra sensitive. A newborn’s skin is up to five times thinner than an adult’s (Cosmetics Design Europe, 2024). That makes it more permeable and more prone to irritation from harsh formulas.
Messy textures. One thing parents mention often: sticky, chalky bottom balms that clump or won’t wipe off easily. Who has time to wrestle with that at 2am?

Why CastorBub barrier cream is different

Biome’s CastorGuard has already earned glowing 5-star reviews for soothing and hydrating dry skin. Now, CastorBub takes this trusted formula into the world of baby care, introducing zinc oxide for gentle protection against nappy rash.

Castor oil (hexane-free) – the star ingredient, known for its silky texture and moisture-locking ability.
Non-nano zinc oxide – with a slightly powdery feel, creates a protective barrier to help prevent nappy rash by shielding skin from moisture, urine, and friction.
Apricot kernel oil & shea butter – soothe and comfort delicate skin.
Natural waxes (carnauba & candelilla) – keep the balm smooth, spreadable, and never sticky.
Vitamin E – helps support and protect the skin.

How CastorBub compares to other creams

Parents often assume all barrier creams are much the same — but the ingredient list tells a very different story. Here’s how CastorBub stacks up against three top-name baby bottom creams found in Australia (full ingredients in the footer if you're interested).

Brand	Key Ingredients	Synthetic / Petroleum Additives?
QV Baby Barrier Cream	Aqua, Zinc Oxide, Dimethicone, Paraffinum Liquidum, Ceteareth-25, Methylparaben	Yes – paraffin, silicones, parabens, synthetic emulsifiers
Sudocrem	Zinc Oxide, Liquid Paraffin, Paraffin Wax, Microcrystalline Wax, Propylene Glycol, Synthetic Beeswax	Yes – multiple petroleum derivatives, synthetic waxes, glycols
Bepanthen	Wool Fat (Lanolin), Liquid Paraffin, Soft White Paraffin, Cetyl/Stearyl Alcohol	Yes – mineral oils, paraffin, alcohols
CastorBub	Hexane-free Castor Oil, Hydrogenated Castor Oil, Carnauba & Candelilla Wax, Apricot Kernel Oil, Shea Butter, Zinc Oxide, Natural Vitamin E	No – 100% natural oils, butter, waxes, and zinc oxide

While mainstream brands rely heavily on petroleum-based fillers and synthetic stabilisers, CastorBub bottom balm is made only with natural oils, waxes, and non nano zinc oxide, giving parents a safer, gentler option for their baby’s delicate skin.

More than just bottoms

Yes, CastorBub is made for babies — but it quickly becomes one of those products you reach for again and again.

A gentle barrier balm for bottoms, chubby cheeks, skin folds, and dry patches — and even useful for the whole family when skin feels irritated or chafed.

Full ingredients of baby barrier creams

QV Baby Barrier Cream: Aqua (Water), Zinc Oxide, Dimethicone, Paraffinum Liquidum, Glycerin, Cetearyl Alcohol, Ceteareth-25, Panthenol, Methylparaben, Xanthan Gum

Sudocrem Healing Cream: Zinc Oxide, Benzyl Alcohol, Benzyl Benzoate, Benzyl Cinnamate, Lanolin, Purified Water, Liquid Paraffin, Paraffin Wax, Microcrystalline Wax, Synthetic Beeswax, Sorbitan Sesquiolate, Propylene Glycol, Antioxidants, Sodium Benzoate, Linalyl Acetate, Lavender Oil

Bepanthen: Purified Water, Wool Fat (Anhydrous Lanolin), Liquid Paraffin, Soft White Paraffin, Dexpanthenol (Provitamin B5), Almond Oil, White Beeswax, Cetyl Alcohol, Stearyl Alcohol, Protegin XN.

CastorBub: Hexane-free Castor Seed Oil, Hydrogenated Castor Oil (from castor beans), Carnauba Wax, *Apricot Kernel Oil, *Shea Butter, Candelilla Wax, **Zinc Oxide, Tocopherol (Natural Vitamin E)

How to use a baby barrier cream

Using a barrier cream consistently can help prevent nappy rash before it starts. Here’s a simple way to incorporate it into your routine:

Apply at every nappy change. Start with clean, dry skin and apply a thin, even layer to protect against moisture.
Focus on key areas. Cover the bottom, skin folds, and anywhere prone to friction or redness.
Use preventatively. Barrier creams work best when used regularly, not just when irritation appears.
Reapply overnight. A slightly thicker layer before longer sleeps can help protect delicate skin for longer periods.

A gentle, breathable barrier helps shield the skin from moisture and friction — two of the main causes of nappy rash.

A simple nappy rash prevention routine

Keeping baby’s skin comfortable doesn’t need to be complicated. A few small habits can make a big difference:

Change nappies regularly to reduce prolonged exposure to moisture.
Allow time for air drying when possible — even a few minutes helps.
Use gentle, plastic free wipes or water to avoid unnecessary irritation.
Apply a barrier cream to protect the skin from moisture and friction.
Choose breathable materials with plastic free nappies and clothing.

Frequently asked questions about baby barrier cream

What does a baby barrier cream do?

A baby barrier cream creates a protective layer over delicate skin to help shield it from moisture, friction, and irritation. It’s commonly used during nappy changes to help prevent nappy rash before it starts.

How often should I apply barrier cream?

Many parents use barrier cream at every nappy change, especially if baby is prone to irritation. It can also be helpful to apply a slightly thicker layer before naps or overnight, when skin may be exposed to moisture for longer.

Can barrier cream be used on broken skin?

If skin is badly broken, bleeding, or showing signs of infection, it’s best to seek medical advice. For mild redness and everyday protection, a gentle barrier cream can help support and shield delicate skin.

What ingredients should I avoid in baby bottom cream?

Some parents prefer to avoid ingredients such as petroleum derivatives, synthetic fragrance, parabens, and silicones in baby care products. Choosing a simpler formula can feel like a gentler option for sensitive skin.

Is zinc oxide good for nappy rash?

Zinc oxide is commonly used in barrier creams because it helps form a protective layer on the skin. This can help shield against moisture and friction, two common contributors to nappy rash.

Can CastorBub be used for more than nappy rash?

Yes — CastorBub can also be used on chubby cheeks, skin folds, and dry patches wherever a gentle barrier balm is helpful. Many families find it becomes a handy all-rounder for irritated skin.

What’s the difference between a barrier cream and a moisturiser?

A moisturiser is designed to hydrate the skin, while a barrier cream is designed to sit on top of the skin and help protect it from external irritants such as moisture and friction. Some products can offer a little of both, but their main purpose is different.