Contraindications and points of attention to consider when using lasers

Indications for the use of laser therapy are many, but there are some important contraindications and other points of attention you should be aware of. Key contraindications are an important consideration, and like other types of treatment (therapy and medication), assessed from a clinical aspect in relation to the patient so that ‘accidental or unforeseen’ side effects may be avoided.,

Older published data regarding lasers often contain contraindications to laser therapy but the truth of the matter is that there is no absolute contraindication to LLLT/PBM, but only relative contraindications and common-sense warnings. The only absolute rule to adhere to is: DO NOT point lasers towards the eye.

Our recommendation regarding laser therapy contraindications is listed and explained below.



A laser class tells you how to protect yourself and others against laser light, so you do not receive accidental eye injury, or possible skin damage. A Laser that power exceeds Class 3R (5 mW but does not exceed 500 mW) is referred to as a Class 3B laser. In the event accidental direct eye exposure, Class 3B laser light may cause temporary eye damage and in certain instances, mild skin damage. It is advisable therefore,  that the correct eye protection goggles(as supplied with our lasers) should always be used, even if there is a slight risk of accidental direct illumination of the eye during treatment times. It is advisable that eye protection goggles should be worn by operator and patient as a matter of routine. If treating animals, a small towel covering their eyes will suffice during treatment.

The power of an electric bulb (W) indicates it´s total power consumption. A 60W electric bulb emits only 1 – 2W visible light. This means that the rest of its power (58-59 W) turns into warm and invisible infrared light. At 1 meter from an electric bulb the pupil of the eye will receive approximately 1 millionth of total light energy.

A laser emitting light as a coherent beam (collimated) will hit the eye with 100% of the light energy, even at vast distances. A laser emitting scattered (divergent) light at 1 meter will hit the eye (Retina) with approx. 0.1% of light energy. At a distance of 20 cm, approx. 10% of the light energy hits the eye. This means that the risk of eye damage from the laser light depends primarily on the beam’s coherence and it´s diameter.

In summary, so long as one does not look directly at the laser light emitted from a Class 3B laser, operators do not need to use eye protection unless they wish to. The patient should always be protected by wearing eye protection if treated near the head.  For lasers in Class 4, both parties should always wear laser protection goggles!



Treating pregnant patients is not a contraindication. Treating pregnant women, for both mother and child, is completely harmless. Direct treatment over or against the undeveloped fetus or pointing the laser at an embryo should be avoided as laser light may inadvertently damage the baby’s undeveloped eyes. Should there be any unintended incidents or complications associated with the laser treatment or soon after, it is easy to blame the laser therapy and the therapist is subsequently burdened with the burden of proof.


Pacemakers, metal implant prosthesis, and internal fixation screws:

For patients with pacemakers, implants or screws, laser therapy is not contraindicated. Pacemakers are electronic and encapsulated in metal and therefore cannot be affected by light. Laser light does not induce ultra-sonic vibration which causes metal to heat up, laser light simply gets reflect by such metal objects.



Epileptic seizures can be induced by certain types of light effects (pulsed visible light in the range 5-10 Hz). One must therefore take care whilst using medical  instruments that produce visible flashing lights. There is however nothing noted in the literature that indicates that invisible pulsating light induces epileptic seizures. From anecdotal evidence it is recommended that whilst treating epileptic patients with lasers, especially if the laser is set to produce PULSED LIGHT rather than continuous light wave output. All Energy Lasers are continuous wave output, so are considered safe to use on all patients, epileptic or not.


Thyroid gland:

It has not been officially reported that LLLT/PBM causes irreversible damage because the thyroid is sensitive to light. Over-stimulation of the Thyroid gland by laser light is best avoided, since it may induce the Thyroid gland to produce an excess of Thyroxine (natural hormone). This is an area of the patient best avoid whenever possible.



The dose should be adjusted to the weight of the child, but there is no indication in the literature that children, including babies, should not benefit from laser therapy. Illumination of epiphysis discs in children is also not contraindicated.



People with cancer, or suspected cancer, should only be treated by a specialist in their field. It is not because laser therapy will not have a stimulating effect, but because the law only allows specialists to treat cancer. Cancer patients can therefore not be treated with laser therapy without a written consent and in collaboration with the doctor responsible for the treatment. As a palliative treatment of patients in the terminal phase, laser therapy can act as both an analgesic and a stimulant, it’s therefore therapeutic.



Patients with haemophilia and other blood and clotting diseases should not be treated with laser therapy at this time, as we don´t know enough about the effect it has on coagulation ability. However, it is more a warning and advisory rather than a contraindication.


Irradiation of the brain:

It can be postulated that brain damage will not occur when areas of the brain are treated. Targeted therapy with laser light of the brain is not recommended so far due to insufficient research data at this time.


Radiation treatment:

Patients receiving radio therapy (Cancer patients) have previously been considered ‘out of bounds’ to laser therapy. It is not obvious why since the radiation they are exposed to has a different characteristic than LLLT/PBM. Laboratory studies on animals receiving X-rays have shown that they make greater progress if they received laser therapy prior to Radio Therapy. Several studies have shown positive ‘local’ effects on the immune system. More and more studies on laser treatment of circulating blood are being published daily.

Changes in blood components in relation to the immune system after laser treatment can obviously lead to effects in many other parts of the body, such as e.g. increased defence against cancer. In fact, LLLT/PBM seems to have a radioprotective effect on tissues and expedites the healing processes.



Diabetes has been suggested as a contraindication. However, there is no evidence that laser therapy can exacerbate the illness. Laser treatment increases blood flow and is necessary for speedy wound healing. Laser therapy has been recommended as an extra treatment modality for diabetic foot problems.


Tattoos, moles and dark skin:

Tattoos, moles, and dark skin (Type 5 and 6 – The Fitzpatrick Chart) contain another pigmentation and even low energy levels of laser light will be quickly absorbed into these pigmented lesions and areas. Depending on the type of pigment, the patient may experience heat or even pain, when a therapeutic laser is used over an area of ​​darkened pigment.  It is recommended to start treatment from a distance. Listen to patient feedback and adjust the laser power (mW) if necessary. Tattoos, moles and other dark skin do not constitute a contraindication clinically, but  high intensity laser light will cause ‘peak absorption’, which often causes local pain. Direct laser exposure over moles and other darker skin lesions is best avoided.



Light sensitivity is often listed as a contraindication for LLLT/PBM. However, there is not much evidence in the literature that confirms the correlation between LLLT/PBM and light sensitivity. On the contrary, several studies show that LLLT/PBM before radiation therapy has a preventive effect. On the other hand, it is known that ultraviolet light can cause photosensitivity. Further research is needed if this alleged contraindication is to be confirmed.


Source: Laser Phototherapy – Clinical practice and scientific background. Tunér and Hode, Prima Books AB 2014


Revised: Energy Laser A/S 2019