Hot Tub vs. Sauna: Which One Wins for Inflammation and Immunity?
When it comes to relaxation and recovery, heat therapy is a fan favourite.
But here’s the million-dollar question: Is a sauna or a hot tub better for your health? A new 2025 study might just flip your assumptions on their head.
Let’s dive into what the research actually says, and how you can use it to level up your wellness routine at Flow Spa.
Hot Tub Takes the Lead—At Least in This Study
A recent study published in the American Journal of Physiology in June 2025, led by exercise physiologist Christopher Minson, published, compared traditional saunas, infrared saunas, and hot tubs to see how they impact inflammation and immune response.
While sauna use is still getting its fair share of the spotlight for health trends, the hot tub produced the strongest physiological effects.
Researchers found that a long soak at 104°F triggered the greatest immune system response and a measurable drop in acute inflammation markers. Why? Because the body experiences more thermal stress in hot water than in heated air.
And while that “heat strain” might sound uncomfortable, it’s actually a key driver of the benefits.
Why Hot Water Has the Edge
Here’s the science in plain English: water transfers heat much more efficiently than air. So even though a sauna might feel hotter, your body heats up faster and to a greater degree in a hot tub.
Let’s break down the temperature comparisons done in this study:
Hot tub: ~104°F (40°C), full immersion for 45 minutes
Traditional sauna: ~175°F (80°C), 3 rounds of 10 minutes with cool-downs in between
Infrared sauna: ~115–150°F (46–65°C), 45 minutes, with the temperature ramping up during the session
This study mimicked casual use you might expect at home, like easing into an infrared sauna while it heats up, or hopping in and out of a traditional sauna between rounds.
But if you’re using these tools intentionally for specific benefits (like we do at Flow Spa), the results may be different.
How You Use It Matters
Here’s an important takeaway: the protocol is everything.
In the real world, most people don’t use heat therapy exactly like they did in the study.
For example:
At Flow Spa, our infrared sauna is fully heated to 150°F when you enter
Many sauna users prefer one continuous 20–30-minute session instead of short intervals
For those looking to get in intense heat, 175°F might sound mild, as many people will push the sauna closer to 200°F
Your mental and physical state going in (hydration, stress level, etc.) can affect how your body responds
So while the hot tub showed impressive immune-boosting potential in the study, that doesn’t automatically make it “better.”
It all depends on your goal and how you use each modality.
What’s Better for You: Sauna or Hot Tub?
It’s not about which one is best, it’s about what’s best for you.
Here’s a quick guide:
Go for a Hot Tub if You Want To:
Boost your immune system naturally
Reduce inflammation after intense training (while heat is initially pro-inflammatory, there is a subsequent anti-inflammatory effect as the body rebounds from the acute effects)
Feel deeply relaxed without moving a muscle
Choose Infrared or Traditional Sauna if You Want To:
Support detoxification and circulation
Loosen stiff muscles and ease joint pain
Stimulate cardiovascular health and mental clarity
Pro Tip: Stack Them for Better Results
Here’s where it gets fun. You don’t have to choose!
At Flow Spa, we encourage strategic recovery combinations.
Try this:
Start in the infrared sauna to warm your body from the inside out
Move to the hot or cold plunge to shock your system (in a good way)
Once you’re done heating up or alternating hot and cold, add a float session or massage to finish in a state of deep calm
This approach doesn’t just feel amazing, it trains your body to adapt, recover, and thrive.
Ready to Feel the Difference?
Whether you’re managing inflammation, supporting your immune system, or just looking for next-level relaxation, we’ve got you covered.
Our team can help you craft a heat therapy routine that aligns with your body and goals.
Book your next session at Flow Spa today to discover what happens when wellness meets intentional heat.