Pain from osteoarthritis (wear-and-tear arthritis) is one of the most common causes of reduced mobility in older adults. It may be the knee, hip, hands, or back that limits everyday life, and many find that the pain fluctuates: calm periods are replaced by days with more stiffness, swelling, and soreness.

Red and infrared light therapy, also known as photobiomodulation (PBM), is increasingly part of the conversation about gentle pain relief. The method is used both in clinics and at home, but it makes sense to start in one place: What does the research say, what can you realistically expect, and how do you use it most sensibly as you get older?

Osteoarthritis in older adults: why pain can become more prominent with age

Osteoarthritis is not just about “wear and tear”. It is a condition where the whole joint can be involved: cartilage, joint capsule, tendons, bone, and local inflammation. Many older adults also have other factors that affect the experience of pain, such as reduced muscle strength, less stability, and a lower activity level.

A short sentence that often hits the mark: It is not always the X-ray that determines the pain, but how the joint functions in everyday life.

The pain may be mechanical (worse with load), inflammatory (worse after rest or in the morning), or a mix. And this is where PBM becomes interesting, because the goal is typically to reduce pain and irritation without putting strain on the stomach, kidneys, or cardiovascular system, as some painkillers can do in older adults.

What red and infrared light therapy is (and is not)

PBM uses light at specific wavelengths, typically red light around 600 to 700 nm and infrared around 800 to 1000 nm. The aim is not to heat the tissue significantly, but to influence biological processes in cells via light absorption.

It is also not a “cure” for osteoarthritis. Osteoarthritis is often a long-term condition where you work with symptoms, function, and load over time. PBM is best positioned as a supplement to the interventions with the strongest evidence for osteoarthritis—especially exercise, weight adjustment when needed, and good everyday strategies.

PBM is now used in several formats:

• Light blankets and large panels
• Light pads and applicators for the knee, shoulder, or back
• Handheld devices and medical lasers (more targeted energy)

The mechanisms: what research points to in the body

The most commonly described mechanism in the literature is an effect on the mitochondria, where light-absorbing enzymes—especially cytochrome c oxidase—appear to be central. When stimulated, the cell’s energy production (ATP) can increase, and nitric oxide (NO) may be released, which is linked to blood flow and signalling in tissue.

At the same time, several review articles describe that PBM may help modulate inflammation by affecting signalling molecules (cytokines) and enzymes involved in tissue breakdown. In an osteoarthritis context, this is relevant because pain and stiffness are often linked to local irritation and an “overactive” tissue environment around the joint.

In older adults, there are no good data showing that the light mechanisms change markedly due to age alone. However, factors that are more common with age can play a role: lower tissue perfusion, slower recovery, and more concurrent complaints. Here, a gentle method that can be used frequently may be practical.

What the evidence says for osteoarthritis: effect on pain and function

When looking at randomised trials and meta-analyses—especially for knee osteoarthritis—the picture is fairly consistent: many studies show pain relief compared with placebo, but the effect varies, and the quality of the evidence is often rated as low.

A newer meta-analysis (2024) found moderate pain relief at rest compared with placebo, while effects on more concrete functional tests, such as walking and sit-to-stand tests, were less clear. An older meta-analysis (2017) also found improvements in pain and WOMAC score (pain, stiffness, and function), but at the same time pointed to large variation in treatment parameters across studies.

This leads to a very practical message: PBM seems able to help many people with pain, while improvements in function often require working at the same time on strength, mobility, and load management.

Many people use PBM with these everyday goals:

• Reducing pain during activity
• Less morning stiffness
• Better tolerance for exercise and walks
• Calming the joint during flare-ups

How long does the effect last?

Most studies measure outcomes immediately after a treatment course or a few weeks later. Here, a positive effect on pain is often seen in some participants. With longer follow-up, the result becomes more uncertain.

In some studies, the difference appears to level out after a couple of months if treatment is stopped completely. This fits well with how many end up using PBM in practice: a more intensive phase when needed and then maintenance if you experience a clear effect.

Protocols in practice: frequency, duration, and “dose”

There is no single standard protocol everyone agrees on. Studies use everything from short, intensive courses to treatment a few times a week for several weeks. A classic research framework is 2 to 3 treatments per week for 4 to 6 weeks, often 10 to 20 minutes per joint per session. Some early studies even used two daily sessions for shorter periods.

An important detail is that “dose” can be reported in different ways: total energy (joules), energy per area (J/cm²), power (mW), and treatment time. WALT (World Association for Photobiomodulation Therapy) has dosing advice, often cited in the range of 2 to 6 J/cm² for pain-relieving purposes in musculoskeletal conditions, but these are not broad national guidelines.

If you use equipment at home, the manufacturer’s instructions will typically be the most useful, because they relate to the specific device’s output, distance to the skin, and the size of the light field. Many home protocols are around 10 to 20 minutes daily, possibly 1 to 2 times a day for a period.

Overview: red, infrared, and laser in relation to osteoarthritis

The table does not say that one type is always better. It says that the format and the way the light is delivered can differ, and that affects what is practical in everyday life.

How PBM can be fitted in alongside exercise and everyday strategies

Osteoarthritis rarely improves from one thing alone. When PBM makes the most sense, it is often as support to help you do what works in the long term: movement.

A simple model is to use the light close to the times when you are normally limited. That might be before a walk to “get the joint going”, or after exercise to reduce irritation.

If you want to make it more systematic, you can consider:

• Timing: before activity (stiffness) or after activity (reaction)
• Period: 3 to 6 weeks with a fixed rhythm before you assess the effect
• Tracking: note pain (0 to 10), sleep, walking distance, and morning stiffness

A short, honest sentence: If you cannot feel any difference after a well-executed period, it is often better to adjust the approach than to simply continue unchanged.

Safety, side effects, and special considerations for older adults

PBM is described in reviews as a method with very few side effects when used correctly. This is one of the main reasons many people with osteoarthritis are curious—especially if they cannot tolerate NSAIDs or want to limit medication.

That does not mean you can use light completely thoughtlessly. The most important precautions relate to eyes, skin, and specific medical conditions.

• Eyes: use protection: Never look into a strong light source or laser, and be extra careful when treating near the face.
• Skin and sensation: With reduced sensation (neuropathy) or sensitive skin, you should start cautiously and monitor the reaction.
• Special conditions: Typically avoid treatment directly over known, active cancer areas, and speak with a doctor during pregnancy or if you use photosensitising medication.

For older adults, “practical safety” is also relevant: being able to place a pad correctly on the knee, sit comfortably, and avoid falling if you stand up immediately after a session.

Why PBM is not in the major guidelines (yet)

Major international guidelines for osteoarthritis still highlight exercise, weight management when needed, patient education, and selected medical treatment and injections in specific cases. PBM is often not mentioned at all.

This is typically not because the method is considered dangerous, but because the evidence is not consistent enough: studies use many different settings, there are often few participants, and long-term data are lacking. When the documentation is uneven, guideline work often sticks to interventions with a more stable evidence base.

This leaves room for a sensible middle position: PBM can be tried as a supplement, especially when the risk is assessed as low, and when you are also working on the measures with the best evidence.

Choosing equipment for home use: what is worth looking for

If you are considering PBM at home, it is an advantage to choose equipment that is CE-approved and where the manufacturer states key specifications. A Danish supplier with stock in Denmark can also make it easier to get guidance, spare parts, and fast delivery.

It is rarely necessary to go for “as much light as possible”. What matters is that the device can be used consistently, close to the joint that is bothering you, and that the instructions are clear.

A small checklist can help:

• Clear wavelengths (red and infrared stated)
• Stated output and treatment area
• User-friendly attachment for knee/hip/shoulder
• Realistic recommendations for use and breaks

When you should speak with a doctor or physiotherapist along the way

PBM can fit into a typical osteoarthritis course, but there are situations where you should not rely on self-treatment alone.

• New, clear swelling and warmth in the joint
• Pain after a fall or twist with suspected injury
• Fever, feeling unwell, or unexplained weight loss
• Night pain that changes character and does not resemble your usual osteoarthritis pain

A physiotherapist can also help you find the exercises that fit your type of osteoarthritis, and in many cases PBM can be used as support to carry them out more consistently.

A realistic goal for many older adults: more movement with less pain

When you look soberly at research and experience, PBM makes the most sense as part of a plan where the goal is better everyday function: being able to walk further, stand up more easily, sleep better, and feel more confident in movement.

Some will notice a clear difference, others only a small one, and some none. The key is that you assess the effect on something concrete in your everyday life, and that you give the method enough time to show its potential—without letting it push the most important measures off your calendar.