Should I apply sunscreen before using a red light device? Will it affect the results?

Many people have a common question before using red light therapy:

“I’ve already applied sunscreen—can I still use red light therapy?”

Some even ask:
“Will sunscreen block all the red light?”

The answer isn’t as simple as you might think.

Today, we’ll take a scientific look at this topic:

✓ Does sunscreen actually block red light?

✓ Why doesn’t it work for some people?

✓ What is the correct sequence for red light therapy?

Why does red light therapy require "light penetration"?

The core of red light therapy (Red Light Therapy / Photobiomodulation) is not simply shining light on the skin's surface, but rather allowing specific wavelengths to penetrate the skin tissue.

Once specific wavelengths penetrate the tissue, the mitochondria within the cells absorb energy, increasing ATP (cellular energy) production, which in turn influences repair, collagen production, anti-inflammatory responses, and metabolic reactions.The biostimulative effects of red light and near-infrared light are now widely described in research as “Photobiomodulation.”

In other words:
If the light cannot effectively penetrate the skin, the results will naturally be less effective.

So, does sunscreen actually block red light?

The real answer:
“It depends on what kind of sunscreen you’re using.”
Current research and spectral analysis show that certain ingredients may indeed affect the transmission of visible or near-infrared light, but not all sunscreens are the same.

Mineral Sunscreen (Physical / Mineral Sunscreen)

Common ingredients:
• Zinc Oxide
• Titanium Dioxide
These ingredients work by:
→ Reflecting light
→ Scattering light
→ Forming a surface barrier

Some studies suggest that these ingredients may affect the penetration of certain visible light wavelengths; therefore, their use is not recommended prior to light therapy in certain applications.

Chemical Sunscreen Chemical sunscreens primarily work by absorbing UV radiation.

Some data suggest they have minimal impact on red light wavelengths, but there is currently insufficient high-quality research to prove they have “no effect whatsoever.”

Therefore.
If the goal is to maximize red light utilization.

the best practice remains:

Clean skin → Apply light first → Then apply sunscreen

Why do so many people feel that red light therapy "doesn't work"? Often,

The problem may not be the device.

It’s the process.

Common mistakes include:

❌ Using the light immediately after applying heavy skincare products

❌ Using the light without first removing sunscreen

❌ Using the light while wearing makeup

❌ Using it for too short a duration

Some experts and clinical guidelines recommend that red light therapy be performed on clean, unobstructed skin to minimize light reflection and scattering.

Med Glow LED Recommended Treatment Protocol

Step 1
Cleanse the skin
Remove:
• Sunscreen
• Foundation
• Makeup
• Heavy skincare products

Step 2
Apply light directly
Recommended duration: 10–20 minutes
Maintain the distance specified in the device instructions.

Step 3
Apply skincare after the treatment
You may then:
✓ Moisturizer
✓ Serum
✓ Sunscreen

Can red light therapy replace sunscreen?

No.
This is a common misconception.
Red light therapy and sunscreen are two completely different things.

Purpose of sunscreen: → Block UV damage

Purpose of red light therapy:
→ Regulate cellular responses
→ Support repair and reduce inflammation
→ Boost skin metabolism

Even though some studies suggest red light may enhance the skin’s resistance to UV damage, this does not mean it can replace SPF.

Conclusion: Don’t rush to apply sunscreen before light therapy if you want to maximize the results of each session.
Remember this simple sequence: Clean Skin → Light First → Skincare Later

Red light therapy isn’t about longer sessions being more effective. Often, the correct sequence is more important than longer duration.