Dehydration: What Do I Need to Know?

Dehydrationdehydration causes

How about we start this article with a little myth busters. Many of you, I am sure have heard this line before:

“Beer has water in it, so I’ll just drink that”- We will answer this shortly

dehydration factsAlthough for some of you out there this may be old news but believe it or not somebody’s mind is going to get blown from this article. (Hopefully)

Let’s start with a definition. What is dehydration? Its as simple as saying “fluid loss.”

Fluid in – fluid out= (Net positive or negative) If negative then you are dehydrated!

In medicine we think of these fluid losses as sensible and insensible losses (trivia fact – you‘re welcome).

Insensible losses (losses you aren’t aware of)

  1. Skin evaporation
  2. Water vapor from breathing

Sensible water losses (This is where you can get in trouble with losing too much fluid)

  1. Gastrointestinal losses: vomiting (seasickness), diarrhea (food poisoning, infection, etc.), bleeding (dark stool or bright red blood in toilet-please please see a doctor)
  2. Renal losses: Some medications (diuretics) increase your losses- you are on these medications sometimes to get rid of fluid, so although I know you don’t want to be drinking too much water, if you are out in the sun fishing you will need too! Alcohol (we will talk about this below)
  3. Skin losses: sweat (fighting the big one or maybe it’s the weather), burns (deeper the burn the more loss but even a sunburn will increase your losses), fever
  4. Third-spacing sequestion: Not important for this article but to be complete we will just mention it. Think of this as inflammation. If something in your body is inflamed, your body pushes fluid out of its circulatory system “blood vessel system” to help the area in need. Ex: Pancreatitis (inflamed pancreas), lots of fluid will go there so these people need to be given lots, lots of fluid back to their “blood vessel system.”

dehydration prevention

Symptoms: Important-with mild dehydration you may not notice any symptoms

  • Thirst
  • Urinating less often, or having dark yellow or brown urine
  • Dizziness or headache
  • Dry mouth or cracked lips
  • No tears when a child cries (adults cry too)
  • Feeling tired or confused
  • Eyes that look sunken in the face (don’t judge)
  • Cramping
  • Increase heart rate
  • Irritable
  • When its really bad we are talking: heat stroke, coma, etc.…
  • Kidney stones: This is usually in the chronic dehydrated person and its cause can be from dehydration as well as (too much salt, too much animal protein, etc.….) These aren’t fun so drink water to eliminate this reason as the cause.

A great marker for dehydration is urination.

In an otherwise healthy person it can be the first sign. Why? Your circulatory system, “blood vessel system” is connected to your kidneys. Imagine a pressurized system. If you drink lots of water you will gain fluid into this system, the pressure increases, and pushes more fluid into your kidneys to filter and make urine. If you have less fluid, resulting in less pressure in the system, less fluid will get pushed into your kidneys and you make less urine.

I’m not happy unless my patients are urinating 0.5 ml/kg/hr. But to make it easy if well hydrated you should make at least about 50 ml of urine an hour. Once your bladder gets to 300 ml you register it as time to go. So you are going about every 6 hours(at least).

This isn’t always reliable, especially if drinking alcohol.

beer boats

Ok let’s cover the topic of alcohol. Some of you may be thinking I always urinate more if I drink alcohol or “don’t break the seal.”

There is a little physiology here but I’ll try to keep it simple. Your body is constantly in check trying to regulate if it needs to conserve water and make less urine or not. Your brain makes a hormone called Anti-diuretic Hormone (ADH). If your body senses it needs to conserve water it makes more of this hormone and within your kidneys there is a pathway that pulls the water back into your body (concentrating your urine-hmm my urine is dark).

alcohol dehydrationAlcohol it turns out inhibits the ADH from working. So that means your kidneys can’t bring the water back and you end up making more urine and this is why you go so much when drinking. Take a look next time you pee when drinking, a lot of the time it isn’t very dark. This is because you are losing water.

Why is this important? You are in the sun (losing water), fishing hard and sweating (losing water), and drinking beer because you are thirsty; you start urinating due to the alcohol inhibiting the ADH (losing water).

Although there is water in beer, the effects of the alcohol exceed its ability to hydrate you.

As you can imagine you could get in trouble quick offshore.

What do I do?

kick plasticAfter all of this I hope you aren’t disappointed when I say drink more water!

Yes you do lose electrolytes too so drinking an electrolyte rich drink like Gatorade or pedialyte is acceptable.

Stay ahead! You can hydrate well before your trip to get a head start!

Drink alcohol in moderation (I know I know, thanks Mom)

If you have diarrhea, vomiting, etc….You need to be extra careful. Drink more (if you can), stay out of sun, etc…. Minimize the losses

beer water

Plan your trip accordingly and bring plenty of water! Maybe even bring Pedialyte (Oral Rehydration System)

For some of you it may prevent the headache and for others it may prevent something severe!


  • Dehydration is fluid loss
  • It can happen even in the winter
  • Sensible losses: Are the ways we lose the majority of our body fluid
  • You may be dehydrated and not feel any symptoms
  • Alcohol will make you dehydrated if you are not also hydrating
  • Drinking water or Oral Rehydration Solution (ex: Pedialyte) will help you hydrate

hot daysThanks for reading. Please stay safe out there and although a few cold ones is a great way to share memories make sure you are getting water as well!

Dr. Brad Genovese
Brad Genovese. I was born and raised in Laguna Niguel, California. He has been greatly blessed to have incredible parents that introduced him to sport fishing, hunting, and travel at an early age. Growing up he spent many summers fishing and diving the Sea of Cortez. Brad says, “Although my entire...