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3 Myths About Class IV Laser Therapy

The use of class IV lasers instead of class IIIB or “cold” lasers for therapeutic applications has been a hotly debated topic. In this article, we’ll talk about some of the myths around class IV laser therapy devices. But first, let’s clarify the difference between class IIIB and class IV lasers.

The FDA classifies lasers based on their power output and their potential to cause eye and skin damage. There’s currently four classes of lasers that range from everyday tools like laser printers and disc drives to lasers used for surgical operations such as LASIK eye surgery, cosmetic hair removal, and tattoo removal.

Laser Class
Laser Printer
Barcode Scanner
Laser pointers (IIIA), research & industrial lasers (IIIB)
Surgical & cosmetic lasers

When it comes to laser therapy devices, class IIIB lasers are often referred to as “cold” lasers. This is because the laser’s power doesn’t have a significant thermal effect. That is, patients won’t feel much or any warming sensation during treatment. Class IIIB lasers have a maximum power output of 500mW (milliwatts, or 0.5W).

On the other hand, class IV laser therapy devices do have a significant thermal effect in superficial tissue if maximum permissible exposure (MPE) limits are exceeded. Read: If used improperly, class IV lasers can cause damage to the skin and eyes. Class IV lasers include any laser that exceeds 500mW of maximum power.


Myth 1: Class IV Lasers are dangerous for laser therapy

The FDA classifies any laser with a maximum power output of 500mW or greater as a class IV laser. This includes:

  • High intensity laser therapy devices
  • Cosmetic hair removal laser devices
  • Surgical lasers, such as those used in LASIK eye procedures
  • Laser light show projectors

That’s a lot of different types of devices with very different applications, and, yes, some of them are extremely dangerous—especially if they’re misused. Lasers are highly concentrated beams of coherent light, and even lower levels of laser light can pose a risk to your vision. If you’ve used a laser pointer, you’ve probably noticed a warning on the device to not shine the beam directly into anyone’s eyes.

Class IV therapy lasers aren’t nearly as powerful as other lasers in the same class, especially compared to those used in surgery. Laser therapy is a noninvasive and painless treatment, and class IV laser therapy devices are no exception.

Training, safety protocol, and appropriate protective eyewear are a must when dealing with any laser therapy device to ensure the safety of your patients and staff. At Aspen Laser, we offer our providers extensive training on our products to ensure proper usage and that safety protocols are understood and followed.


Myth 2: Class IV Therapy Lasers don’t necessarily penetrate to deeper tissues

Light energy, which is expressed in Joules, is readily adsorbed by plenty of materials, including body tissue. This means that when a laser is applied to a patient’s skin, their body will absorb about half of that energy before it reaches the appropriate depth for treatment in some cases. So, a higher energy of light at the surface will translate to a lower dosage deeper in the body. Class IV laser therapy devices have the power to deliver proper treatment dosages in deeper tissues with higher power applied properly at the skin.

Additionally, there is an optimal dosage range that is dependant on the injury or condition being treated. That is to say, different problems will need different levels of power. For example, one double-blind study conducted on the effects of class IV laser therapy on blood flow and circulation found that 3W of power produced improved blood flow to the forearm of participants, but 6W of power wasn’t effective.

“More” doesn’t always translate to “better.” Aspen Laser’s therapy devices allow providers to treat their patients with the correct amount of infra-red laser light for their situation with adjustable power outputs from 1 to 60 watts.


Myth 3: Class IV Therapy Lasers can damage healthy tissue/skin

If your patients’ skin will get the brunt of the laser power, you might be worried about damage to healthy tissue. This is not the case. In The Laser Therapy Handbook, authors Jan Turner and Lars Hode point out that healthy tissue can handle nearly any dose of infra-red light without negative effects. For example, surgical lasers that operate at much higher powers in order to cut, evaporate, or coagulate tissue do not cause any damage or negative side effects to the surrounding tissue, despite these areas also receiving fairly high dosage of laser light.


Aspen Laser has 30 years of combined experience developing laser therapy devices on our management team, and we’re committed to raising standards of medical care to improve the quality of life in every patient. To learn more about the difference in class IIIB and class IV lasers, visit our education site, Aspen Laser University.

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