Sunscreen 101: Physical vs Chemical. What’s the Difference, Which Is Safer, and How to Choose.

Sunscreen labels can feel overwhelming. Physical, mineral, chemical, organic, reef-safe, pregnancy-safe, etc...the terminology alone is enough to confuse even the most skincare-savvy reader.

Yet sunscreen remains the single most important step in any routine. Not only for preventing sunburn, but for protecting long-term skin health, slowing visible aging, and keeping pigmentation under control.

So let’s slow things down and clarify what actually matters.

Physical (Mineral) Sunscreens: How They Work

Physical sunscreens, also called mineral sunscreens, use two main UV filters: zinc oxide and titanium dioxide.

These minerals sit on the surface of the skin and primarily scatter and reflect UV radiation. They also absorb a small portion of UV energy and convert it into heat at the particle’s surface, which is then released harmlessly.

From a protection standpoint:

• Zinc oxide offers the most complete coverage, protecting against both UVA and UVB rays.
• Titanium dioxide provides strong UVB and UVA2 protection but is weaker against UVA1, which is why it’s often paired with zinc.

Why many people prefer mineral sunscreens:

Mineral formulas are widely considered the gentlest option, especially for:

• sensitive skin
• rosacea- or eczema-prone skin
• post-procedure or compromised barriers

They provide immediate protection (no waiting time after application) and have the lowest systemic absorption, which is why they’re often recommended during pregnancy and for children.

The trade-offs

Mineral sunscreens can feel thicker and may leave a white cast, particularly on deeper skin tones. Modern formulations and tinted versions have improved this significantly, but texture and finish remain a deciding factor for many users.

 

Chemical (Organic) Sunscreens: How They Work

Chemical sunscreens, sometimes called organic sunscreens, work differently. Instead of sitting on the surface, their filters absorb UV radiation and convert it into a very small amount of heat, which is then released from the skin.

Older, widely known filters include:

• Avobenzone
• Octisalate
• Octocrylene
• Homosalate

More modern filters, commonly found in European and Korean sunscreens, include:

• Tinosorb S & M
• Uvinul A Plus
• Uvinul T 150

These newer filters are more photostable, better tolerated, and provide excellent high-UVA protection.

Why people love chemical sunscreens

Chemical sunscreens are often praised for their:

• lightweight, elegant textures
• invisible finish
• ease of wear under makeup
• suitability for deeper skin tones

For many people, these formulas are simply more comfortable to wear daily, and consistency matters!

Potential downsides

Some chemical filters can cause stinging or irritation, particularly around the eyes or on sensitive skin. Certain legacy filters, such as oxybenzone, have raised concerns related to sensitivity, hormone disruption, and environmental impact, which is why many regions and brands now avoid them.

 

Which Sunscreen Is Safer During Pregnancy and Breastfeeding?

This is one of the most common and important questions.

During pregnancy

Most dermatologists agree on a conservative approach:

First choice: mineral sunscreens containing zinc oxide and/or titanium dioxide, as they have a minimal absorption rate and a long-established safety profile.

Many chemical sunscreens are still considered acceptable, but oxybenzone is generally advised against during pregnancy. If using chemical formulas, modern filters with good tolerability are preferred, and any product that stings or irritates should be discontinued.

During breastfeeding

The same preference applies:

• Mineral first when possible
• If applied to the body, keep away from the areola
• Wash hands before feeds

Sunscreen for Children: Why Mineral Is Preferred

When it comes to children, mineral sunscreens are considered the safest first choice.

Why mineral works best for kids

• Zinc oxide and titanium dioxide sit on top of the skin
• Very low absorption
• Least likely to sting eyes or trigger irritation
• Immediate protection

Age-specific guidance

• Under 6 months: avoid direct sun; use shade, hats, and UPF clothing. If unavoidable, a small amount of mineral SPF may be applied to limited areas.
• 6 months and older: broad-spectrum mineral SPF 30–50 when outdoors.

What to avoid

• Fragrance, essential oils, and alcohol-heavy formulas
• Spray sunscreens (inhalation risk, uneven coverage)
• Filters known to sting sensitive skin

Sunscreen should always be paired with shade, hats, sunglasses, and UPF clothing.

Reef Safety: What Actually Matters

“Reef-safe” has become a popular marketing term, but it’s not regulated.

What we do know:

• Regions such as Hawaii and Palau restrict sunscreens containing oxybenzone and octinoxate due to coral toxicity concerns.
• Non-nano zinc oxide is generally considered the most reef-friendly option available.

If marine impact is a priority for you, look past marketing claims and check ingredient lists carefully.

Why Sunscreen Is Truly Non-Negotiable

Sunscreen is not just about avoiding sunburn.

• UVB rays cause burns and contribute to skin cancer.
• UVA rays penetrate deeper, damaging DNA, accelerating aging, and worsening pigmentation.
• Visible light, especially in deeper skin tones, can exacerbate melasma and post-inflammatory hyperpigmentation.

This is why tinted sunscreens with iron oxides are often recommended for pigmentation concerns, as they help block visible light in addition to UV.

How to Choose the Right Sunscreen for Your Skin

Rather than asking “Which is better?” the better question is “Which will I actually use correctly?”

• Sensitive, rosacea, or eczema-prone skin:
  Mineral sunscreen, fragrance-free, soothing base. (e.g. Axis-y Complete No-Stress Physical Sunscreen) 
• Oily or acne-prone skin:
  Lightweight chemical fluids or sheer mineral serums labeled non-comedogenic. (e.g. Tocobo Cica Calming Sun Serum or Boj Relief Sun: Rice + Probiotics) 
• Dry or dehydrated skin:
  Modern chemical sunscreens with a moisturizing factor. (e.g. Skin1004 Madagascar Centella Hyalu-Cica Water-Fit Sun Serum) 
• Melasma or pigmentation concerns:
  Daily tinted sunscreen (iron oxides), wide-brim hat, and diligent reapplication. (Coming soon to Nari)

Smart Sunscreen Use: What Really Drives Results

Even the best formula fails if it’s under-applied.

• Amount: about 2 mg/cm² (roughly two finger lengths for face and neck)
• Timing: last step of your morning routine
• Reapplication: every 2–3 hours outdoors, and after sweating or swimming
• Layering: moisturizer → sunscreen → makeup
  (Vitamin C goes on before sunscreen in the morning.)

The Bottom Line

There’s no single “perfect” sunscreen, only the one you’ll use correctly and consistently.

• For pregnancy, children, and ultra-sensitive skin: mineral is the safest bet
• For deeper skin tones or texture-sensitive users: modern chemical or tinted mineral formulas improve wearability
• For the ocean: avoid oxybenzone and octinoxate, choose non-nano zinc when possible
• And above all: apply generously, reapply often, and use sunscreen every single day

Consistency, not perfection, is what protects your skin for life!