Staying Hydrated in the Sauna: What You Need to Know

Why hydration matters in saunas?

Stepping into a sauna feels amazing, but without proper hydration, your relaxing session can quickly turn uncomfortable. When you sweat a lot, your body has trouble cooling itself. Dehydration symptoms include dizziness, nausea, and rapid heartbeat, potentially leading to heat stroke. Let’s explore the essential relationship between saunas and hydration, and how to keep your body balanced during those sweaty sessions.

How Much Water Weight Can You Lose in a Sauna?

In a typical sauna session, you can lose approximately 0.5 kg (~1 pound) of water weight through sweating. This varies based on:

• Your body composition (more muscle mass = more sweat)
• Session length
• Sauna temperature
• Your personal sweat rate

This weight loss, however, is temporary water weight—not fat—and will return once you rehydrate properly.

Does Sauna Help with Water Retention?

Saunas can temporarily reduce water retention through increased sweating, but the effect is short-term. For those dealing with water retention:

• The heat helps expand blood vessels and improve circulation
• Sweating eliminates excess fluid and some toxins
• After rehydrating, your body’s natural balance typically returns

However, saunas aren’t a long-term solution for ongoing water retention problems, which often require addressing underlying causes.

This matters most for people with kidney or heart problems. Healthy people rarely need to worry about this.

Preventing Sauna Headaches

Getting post sauna headaches? They’re usually from dehydration. To avoid them:

• Drink plenty of water before your sauna session
• Keep water nearby during your sauna session. Plain water works best. It can also be useful to have one with some electrolytes (see below).
• The best is to consume room temperature water because your gut absorbs it more easily
• Avoid alcohol before and during sauna use as it causes rapid dehydration
• Start with shorter sessions as your body adapts

When you sweat in a sauna, you’re not just losing water—you’re losing essential minerals that keep your body functioning properly:

• Potassium: Supports heart rhythm and muscle function
• Magnesium: Critical for muscle relaxation and energy production
• Calcium: Necessary for muscle contraction and nerve signaling
• Sodium and Chloride: Maintain fluid balance and support nerve function

This is especially important for those having an active life and enjoying sauna quite often. While you might not notice any difference at first, having multiple sauna days will take its toll. Don’t wait that long.

Best Way to Restore Electrolytes After Sauna

After a good sweat, replenishing electrolytes is crucial. Here’s how:

1. Hydrate with electrolyte-rich fluids: Water with a pinch of salt or sports drinks
2. Eat electrolyte-rich foods:
   • Potassium: Bananas, avocados, spinach
   • Magnesium: Nuts, seeds, dark chocolate
   • Calcium: Dairy products, leafy greens
   • Sodium: Pickled foods, broths

Drink water throughout the day and during your sauna. Save food for later if it makes you uncomfortable.

Smart Sauna Hydration Habits

For the best sauna experience:

• Bring a bottle with room-temperature water
• Take regular cooling breaks—this is when your body core temperature continues adjusting
• Use these breaks to rehydrate and let your body recover
• Save any alcoholic beverages (beer, cider, etc.) for after you’re fully cooled down and rehydrated

When to Be Cautious

While saunas offer many benefits, be extra careful with hydration if you:

• Have heart conditions
• Are pregnant
• Take medications that affect fluid balance
• Have kidney problems

Remember, proper hydration isn’t just about comfort—it’s essential for safely enjoying all the wonderful health benefits saunas have to offer. Listen to your body, drink plenty of fluids, and replenish those vital electrolytes.

Considerations for Children

Children, like adults, can easily forget to drink enough water, especially when having fun. It’s the supervising adult’s responsibility to ensure they stay hydrated. For more detailed guidance, refer to Kids in Sauna: A Comprehensive Guide.