Post-Concussion Syndrome & Heat: Your Symptoms Set the Limit
Persistent concussion symptoms have treatments with real evidence.
Far infrared isn't one of them — and heat can set symptoms off.
Symptoms That Linger Deserve a Proper Evaluation
If concussion symptoms last longer than expected, see a clinician experienced in concussion care. If symptoms are getting worse, or you have repeated vomiting, a seizure, confusion, weakness, or a severe worsening headache, get emergency care. If low mood or hopelessness is part of this, tell your clinician — and in the US, call or text 988 in a crisis. Nothing on this page is a treatment.
Understanding Persistent Post-Concussion Symptoms
Most people recover from a concussion within weeks, but some don't. When symptoms — headaches, dizziness, fatigue, trouble concentrating, poor sleep, mood changes, sensitivity to light and noise — last well beyond the usual recovery window, it's called post-concussion syndrome, or “persistent post-concussion symptoms.”
Estimates of how many people are affected vary widely, from roughly 10% to more than 30% depending on how it's defined, and the underlying cause isn't fully understood. Far infrared gets pitched for exactly these symptoms. Here's what's actually known.
What the Research Actually Shows
No Direct Far Infrared Trial Identified
No trial of far infrared sauna or far infrared devices in post-concussion syndrome that we could find. Any effect on headaches, fatigue, sleep, brain fog, or recovery is untested. The closest far-infrared work is in other brain-injury and disease models (rat stroke, Alzheimer's mice) and doesn't involve concussion — see our companion Traumatic Brain Injury page.
Where the Evidence Actually Is for Persistent Symptoms
One of the better-studied options is clinician-guided aerobic exercise kept below the effort level that provokes symptoms.
In a randomized trial of 81 adults with persistent symptoms and exercise intolerance 3 to 24 months after a mild brain injury, a physical-therapist-guided program of this kind raised the effort level people could reach on a treadmill test before symptoms flared — about 136 to 158 beats per minute, versus 147 with general advice alone — and the effect lasted at 6 months.
Overall symptom scores didn't differ between the groups, though (Valaas et al. 2026, Physical Therapy). An earlier randomized trial (ACTBI) comparing a 6-week program of this kind with stretching supported prescribing aerobic exercise to adults with persistent symptoms, as preliminary evidence. A systematic review rates the overall evidence for graded exercise as low to moderate certainty.
This is something to discuss with a clinician — not a program to start on your own, and not a sauna.
Why Heat Needs Extra Care When Symptoms Are Easily Provoked
Many people with persistent symptoms have exercise intolerance — symptoms that flare or come back during exertion. In one clinic study of 100 adults 3 to 24 months after a mild brain injury, 81% tested positive on a treadmill test.
Why this happens isn't well understood; researchers suggest it may involve how the brain's blood flow responds to exertion and problems with the autonomic nervous system, which controls heart rate and blood pressure.
We found no study of how people with persistent symptoms tolerate heat. But heat also raises heart rate and shifts blood flow, so a flare in a warm room, a hot shower, or a sauna is useful information, not something to push through.
The best-supported active approach keeps effort below the point that provokes symptoms. The same idea — stop before symptoms flare — is a sensible precaution with heat, though no one has tested heat that way, and we're not offering a heat protocol.
Before You Try Heat With Post-Concussion Symptoms
- Recent concussion, or symptoms that are getting worse: don't start heat therapy. Get evaluated first.
- If heat already triggers symptoms — headache, dizziness, fatigue, nausea, brain fog — take that seriously. Stop, and tell your clinician.
- Headaches: in a depression trial of strong whole-body heating, headache was the most common side effect (13 of 15 people in the heated group). Different population and a much stronger heat dose, but relevant if you get post-traumatic headaches or migraines.
- Dizziness and balance: heat widens blood vessels, and standing up afterward can make lightheadedness worse. Get up slowly, and don't do this alone.
- Seizures: if you've had a seizure or have epilepsy, ask your neurologist first. One hyperthermia trial lists epilepsy as an exclusion.
- Medications: some affect sweating, blood pressure, or alertness. Check with your prescriber.
- Start much shorter and cooler than you think you need, and stop at the first sign of a symptom flare.
- This isn't a treatment and doesn't replace evaluation, rehabilitation, or follow-up care.
What We Can Honestly Say
There's no evidence that far infrared helps post-concussion syndrome. If your symptoms are stable, your clinician agrees, and a short, gentle session doesn't bring anything on, it can be a comfort choice — but it isn't a therapy, and the options with evidence behind them are worth pursuing first.
For related context, see our companion Traumatic Brain Injury, Sleep, Stress & Mood, Depression, Anxiety, and HPA Axis pages.
Sources
Valaas et al. 2026 (Phys Ther 106(6):pzag049); ACTBI randomized trial (Arch Phys Med Rehabil); exercise intolerance in 100 adults with persistent post-concussion symptoms (PMC12604302); autonomic cardiovascular function and exercise intolerance after mild TBI (PMC12159307); Hocke et al. 2018 (J Neurotrauma 35(11):1224–1232) and a 2024 nature-based intervention pilot (PMC11273594) for prevalence estimates; functional overlay model of persistent post-concussion syndrome (PMC10377031); Mason et al. 2025 (Glob Adv Integr Med Health; NCT05708976); NCT06204458 (epilepsy exclusion).
