Do Cold Plunges Lower Blood Pressure?

KEY TAKEAWAY: No cold plunges do not lower blood pressure in the short term. They raise it. A 15-minute immersion at around 10°C lifts systolic blood pressure from a resting ~111 mmHg to ~135 mmHg within the first minute, and it stays elevated at around 125 mmHg 30 minutes after getting out (Reed et al., 2023). The best-available 2025 meta-analysis of 3,177 participants found no consistent long-term blood pressure reduction from cold water immersion (Cain et al., 2025). If you have high blood pressure, a heart rhythm disorder, or cardiovascular disease, do not use cold plunging as a treatment and don’t start one without clearing it with your GP first.

The first second in 10-degree water punches the air out of your lungs. Your shoulders ride up, your breath goes shallow and fast, your heart thumps against your ribs. Then something interesting happens you settle, the breathing slows, and by the time you climb out you feel oddly calm. That contrast between the gasp and the afterglow is why cold plunging took off, and it’s also why so many people now ask whether a regular ice bath could bring their blood pressure down.

It’s a fair question. Blood pressure is the most common chronic health issue in Australia around one in three Australian adults has high blood pressure, and most people only find out when a cuff tells them. If cold water could help with that, it would matter. The problem is the evidence doesn’t line up with the wellness-TikTok version of the story. A lot of blogs currently ranking for this query quote a University of Oregon press release saying cold plunges “reduced” blood pressure. The actual paper shows the opposite. We’ll walk through what the studies measured, what they found, and who should stay out of the water entirely.

Just as cold plunges temporarily raise blood pressure, they also impact hormones—contrary to popular belief, studies show they lower testosterone levels rather than increase them.

This guide pulls together the 2023 Reed/Minson study everyone keeps misquoting, the 2025 UniSA meta-analysis (the biggest review on the topic to date), and the current safety position from Royal Life Saving Society Australia. If you’re still weighing up whether to buy a plunge, you can see our comparison of the best ice baths.

SAFETY FIRST – READ BEFORE YOU PLUNGE: Do not use cold plunging to treat high blood pressure. Cold immersion raises blood pressure acutely. If you have uncontrolled hypertension, a heart rhythm disorder (including atrial fibrillation), coronary artery disease, Raynaud’s, or peripheral artery disease, do not plunge without medical clearance. Start at 15°C for 1–2 minutes, not 5°C for 10 minutes. Cold shock response starts below 15°C. Royal Life Saving AU considers 10–15°C the safe range for most healthy adults. Never plunge alone. A spotter matters even more than the temperature. An involuntary gasp while your head is under is how cold-water drownings happen. If you’re over 50, pregnant, on beta-blockers or blood pressure medication, or have any cardiac history talk to your GP first. A resting ECG is a reasonable precaution. cold plunges for anxiety and depression

Blood pressure and cold plunges at a glance

The short answer changes depending on which phase you’re asking about entering the water, during the plunge, 30 minutes after, or after months of regular use. Here’s how the evidence breaks down: are ice baths dangerous ideal ice bath temperature

Note: magnitudes vary with water temperature, immersion depth, participant age and habituation. All BP numbers above are approximate group means from the cited studies in healthy, young adults. are ice baths good for you

The short answer (and why it keeps getting reported wrong)

SECTION TAKEAWAY: Cold water immersion acutely raises blood pressure via sympathetic nervous system activation. No high-quality evidence shows a consistent long-term reduction in resting blood pressure from cold plunging. The 2023 University of Oregon study widely cited as proof of BP reduction actually shows the opposite in the published data. best portable ice baths

The reason this question keeps bouncing around is a press release. In May 2024, the University of Oregon ran a story titled Cold plunging might help heart health, new research suggests, which claimed researchers “found a significant reduction in participants’ heart rate, blood pressure and … cortisol after the cold plunge.” That sentence got quoted across dozens of wellness blogs.

If you read the actual paper (Reed et al., Journal of Thermal Biology, 2023), the blood pressure figures tell a different story. Sixteen healthy adults sat in 10°C water up to the sternum for 15 minutes. Their systolic blood pressure went from 111 mmHg at rest to 135 mmHg at the one-minute mark, was still 119 mmHg at 15 minutes in the water, and was 125 mmHg 30 minutes after they got out. Diastolic and mean arterial pressure followed the same pattern. There was no point during the study at which blood pressure was lower than baseline.

Heart rate did drop below baseline after the initial spike from 76 bpm at rest to 63 bpm at 30 minutes post-immersion which is what the press release seems to have conflated with blood pressure. The paper itself is honest about it. The authors conclude that “an acute bout of cold water immersion minimally affects shear stress patterns” and that cold plunging may not be a useful modality for targeting vascular function.

What happens to your blood pressure when you step into 10°C water

Cold on skin is a strong sympathetic stimulus. Skin thermoreceptors fire, the hypothalamus kicks off the “fight or flight” response, and noradrenaline floods the bloodstream. Three things happen in the cardiovascular system almost at once:

• Peripheral vasoconstriction. Blood vessels in the skin and extremities clamp down to shunt blood to the core. This increases total peripheral resistance, which is the denominator that drives blood pressure up.
• Cold shock response. Below about 15°C, you get an involuntary gasp, a spike in breathing rate, and a surge in heart rate within the first 30 seconds. Royal Life Saving AU describes this as the reason cold-water drownings can happen within a minute.
• Catecholamine release. Noradrenaline can rise sharply with cold exposure. In one often-cited study, a one-hour immersion at 14°C raised noradrenaline by around 530%. The key caveat almost never included in blog posts citing this number is that the spike scales with duration. A 2-minute dip is nowhere near a 1-hour one.

The net cardiovascular effect of these three responses is a rapid jump in blood pressure. Harvard Health puts it bluntly: the shock of cold water on the skin “speeds up your heart rate and blood pressure” and the extra adrenaline can disrupt the heart’s rhythm. For a healthy heart this usually isn’t a problem. For someone with untreated hypertension or an arrhythmia, it can be.

What the University of Oregon (Reed et al., 2023) study actually measured

SECTION TAKEAWAY: Reed 2023 measured 16 healthy young adults in a 15-minute, 10°C plunge. Systolic blood pressure rose from 111 to 135 mmHg and stayed elevated through the 30-minute recovery period. Heart rate dropped below baseline after an initial spike. Cortisol was lower three hours after immersion. Blood pressure was never below baseline at any measured timepoint.

Because this study is quoted so often and quoted incorrectly it’s worth laying out exactly what the measured numbers were. The study used a hydraulic chair to lower participants to sternum depth in circulating 10.5°C water for 15 minutes, then transferred them out. Blood pressure was measured at rest, at 1 minute and 15 minutes in the water, and 30 minutes after exit. Here’s what the published data showed (mean values):

Source: Reed et al., Journal of Thermal Biology, 2023. Arrows indicate direction vs pre-immersion baseline. All changes were statistically significant at p<0.05.

The reason heart rate drops below baseline after the initial spike while blood pressure stays elevated is that peripheral resistance is carrying the pressure load. The vessels are clamped. The heart doesn’t have to beat fast to maintain pressure when the pipes are narrow. This is an important distinction: a lower heart rate is not the same thing as a lower blood pressure. The press release blurred the two. The paper didn’t.

Can cold plunges lower blood pressure long-term?

SECTION TAKEAWAY: Long-term evidence is thin and mostly non-randomised. The strongest single pointer is a small 1988 US Army study (n=7) where 5 weeks of daily 90-minute immersions at 18°C reduced the BP response to subsequent cold exposure a habituation effect, not a reduction in resting blood pressure. The 2025 UniSA meta-analysis of 3,177 participants did not find consistent long-term blood pressure reductions from cold water immersion.

There are three separate questions hiding inside “does cold plunging lower BP long-term?” and blurring them is how the wellness internet ends up arguing with itself.

Question 1: Does regular cold exposure blunt the acute BP spike?

Yes, but modestly, and this is habituation, not treatment. Muza et al. (US Army Research Institute of Environmental Medicine, 1988) followed seven healthy men through five weeks of daily 90-minute immersions in 18°C water. By week 5, their blood pressure response to cold was smaller than in week 1. Hirvonen et al. (2000) found similar habituation in long-distance winter swimmers: diastolic pressure rose less after four days of repeated swims than on day one. Keatinge’s 1980 study of 28 habitual “ice-bears” in London found their systolic BP spiked most while standing undressed in cold air before getting in the water, and returned to baseline within four minutes of exit.

So the cold plunge feels less cardiovascular stressful the more you do it. That’s real. It does not mean your resting blood pressure, measured at a GP the next morning, is lower.

Question 2: Does cold plunging lower resting blood pressure measured on a different day?

There is no high-quality randomised trial that shows this. The Cain et al. (2025) meta-analysis from UniSA the largest review on cold water immersion’s health effects, covering 11 studies and 3,177 participants found benefits for stress (at 12 hours post), sleep quality, and quality of life, but did not find consistent long-term reductions in resting blood pressure. The 2025 Harvard Health review concludes the same: the cardiovascular case for cold plunging is driven mostly by small improvements in heart rate variability, not blood pressure, and those improvements haven’t been shown to translate into better heart outcomes.

Question 3: What about brown fat, nitric oxide, mitochondria – the mechanistic case?

A lot of wellness content leans on mechanistic stories: cold activates brown adipose tissue, improves endothelial function, increases mitochondrial biogenesis, therefore lowers blood pressure. Mechanisms are plausible and parts are supported in animal and in-vitro data. But plausible mechanism is not the same as a measured outcome in humans. If a five-week protocol of 90-minute immersions in seven men is the strongest human evidence on long-term BP, the honest answer is: we don’t yet know.

What the 2025 UniSA meta-analysis actually said

The Cain et al. 2025 meta-analysis, out of the Alliance for Research in Exercise, Nutrition and Activity at the University of South Australia, is currently the most comprehensive review of cold water immersion’s effects on general-population health. It pooled data from 11 studies with 3,177 participants and tested outcomes at several time points: immediately post, 1 hour post, 12 hours post, 24 hours post, and 48 hours post.

The headline findings were:

• Stress: significantly reduced at 12 hours post-immersion. Not immediately the stress response is up immediately. It’s the lagged downshift that matters.
• Sleep quality: modest improvement over the following night.
• Quality of life: small but positive effect.
• Mood: no consistent effect.
• Immunity: acute spike in inflammation followed by recovery. No evidence of a sustained anti-inflammatory effect.
• Blood pressure: the authors state directly that cold water immersion “can acutely increase heart rate and blood pressure.” They did not find consistent long-term reductions.

The UniSA authors are careful to say this is nuanced and time-dependent, and they warn against treating cold plunging as a health intervention for the general population without more research. The 12-hour stress reduction is the most solid finding and it’s not the same thing as lower blood pressure.

Who should never cold plunge

HARD CONTRAINDICATIONS Do not cold plunge if you have: • Uncontrolled high blood pressure (systolic >160 or diastolic >100 consistently) • Atrial fibrillation or any diagnosed heart rhythm disorder • Coronary artery disease or previous heart attack • Peripheral artery disease or Raynaud’s syndrome • A pacemaker or implantable defibrillator (talk to your cardiologist) • Pregnancy especially third trimester • Cold urticaria (cold-induced hives) or cryoglobulinemia

This list isn’t conservative hedging. The American Heart Association, Harvard Medical School, Mayo Clinic, and Royal Life Saving Australia all flag the same conditions. If a brand’s marketing makes cold plunging sound safe for “everyone,” it’s wrong. That’s the cut-the-BS bit: if a product page doesn’t carry a contraindications section, take the health claims with salt.

If you’re on blood pressure medication particularly beta-blockers have that conversation with your GP before you start. Cardiologists have raised concern that beta-blockers and similar agents can blunt the body’s ability to respond to the sudden temperature drop, which is a different kind of risk to the one most users are thinking about.

What actually lowers blood pressure (and how cold plunges fit in)

SECTION TAKEAWAY: If your goal is lower resting blood pressure, the evidence-based interventions are aerobic exercise (30 min most days), a DASH-style diet, weight loss if overweight, reduced alcohol, reduced sodium, and if prescribed medication. Cold plunging is not on the list. Sauna bathing actually has more evidence for BP reduction than cold immersion does.

The Heart Foundation of Australia and the Royal Australian College of General Practitioners both list roughly the same first-line strategies for lowering blood pressure: aerobic exercise most days, a DASH-style diet, limiting sodium to under 2,000 mg daily, weight management, and limiting alcohol. These are the interventions with randomised-trial evidence behind them.

Interestingly, heat exposure has stronger evidence for blood pressure reduction than cold does. Regular sauna bathing has been associated with lower blood pressure and reduced cardiovascular mortality in Finnish cohort studies. Contrast bathing (sauna alternating with brief cold exposure) is where cold immersion may have the most defensible cardiovascular rationale not cold on its own.

That doesn’t mean cold plunging is useless. The 12-hour stress reduction, the dose-response for muscle soreness recovery, and the mood effects on negative affect are real. They’re just not “lowers blood pressure.”

8. Australian-specific considerations

Most ice bath content online is written for northern-hemisphere climates. A few things change when you’re running a plunge in an Australian home:

Tap water temperature varies wildly by state

In Melbourne or Hobart in July, cold tap water can be around 8–12°C straight from the mains already in cold shock territory. In Darwin in February it can exceed 28°C, which means your chiller is doing all the work. This matters for blood pressure because the same instruction to “fill from the tap and plunge” produces very different cardiovascular stress depending on where and when you’re doing it. Colder starting water means a larger acute BP spike.

Older homes, no thermometer, no spotter

The biggest AU-specific safety issue we see in user feedback is DIY setups where nobody’s actually measuring the water temperature. A cheap floating pool thermometer costs under $15 at Bunnings or BCF. Use one. “It feels really cold” and “it’s 7°C” are not the same data point, especially if you’re plunging before anyone else is awake.

GP access and pre-plunge screening

If you’re over 50, or have any cardiac family history, book a GP appointment before your first plunge. A resting blood pressure check and an ECG are standard, covered by Medicare if there’s a clinical reason, and take 15 minutes. Compared to the cost of a plunge tub, it’s negligible.

Frequently asked questions

Medical disclaimer: This article is general information based on current research and is not medical advice. Cold plunging carries real cardiovascular risks for some people. If you have hypertension, a heart condition, are pregnant, are over 50, or take prescription medication, speak with your GP or cardiologist before starting cold water immersion.