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Hydration is important after surgery, but why? It’s something you hear all the time → stay hydrated, make sure you drink lots of fluids. Your mom said it, your coach said and now your surgeon says it. The problem is, no matter how much you drink, it never seems to be enough for your loved ones who keep pushing more fluid. And going to the bathroom every hour after surgery isn’t exactly a walk in the park.

What exactly does hydration do for you after surgery and how do you know when you are adequately hydrated?


The body is made up mostly of water. It contain blood that carries oxygen and other elements that initiate the healing process and provide the required oxygen the tissue needs to repair itself.

When tissues are dehydrated and the circulating volume of blood in the body decreases, the blood becomes “thicker”. Think of it like cake batter, when you add flour the batter gets thicker and hard to move with a spoon. If you add liquid, the cake batter becomes runny and easier to move. Your blood moves the same way. When you are dehydrated, the blood gets thicker and hard to move. It can also start to clump and form clots.

One of the most dreaded post-operative complications is the formation of a clot in the major veins of the legs called deep vein thrombosis. The clot itself can cause lower extremity pain and swelling, but it also has the potential to dislodge and get stuck in the lung → called a pulmonary embolism.

Hydration has long been thought to play a very important role in preventing blood clots for forming. Studies* show that dehydration alone can be linked to the development of clots in the leg, so it’s certainly not speculation or your mom being overprotective. There is real evidence that adequate post-operative hydration is non-negotiable.

*Keiter, J., Johns, D. & Rockwell, W. (2015). Importance of postoperative hydration and lower extremity elevation in preventing deep venous thrombosis in full abdominoplasty: A report on 450 consecutive cases over a 37-year period. Aesthetic Surgery Journal, 35(7), 839-841.


Some patients are afraid to drink too much water after surgery because they fear that it will cause more swelling at the site and perhaps even make it worse. Swelling occurs because the tissue has been cut. Swelling is the body’s way of protecting the area. Water is actually pulled from the vessels into the tissue, which leaves the circulating volume of the body. You need to replenish that fluid. Drinking more water will not cause more swelling, but it will facilitate blood flow to the incision, which is what is extremely important for proper wound healing.

Keeping hydrated is a great way to promote blood flow and prevent blood clumping.

If you want to decrease the swelling, you need to constrict the blood vessels to prevent water from leaking into the tissue in the first place. The best way to accomplish this is by placing ice on the incision. A quick trick for icing an incision? Keep a store of fruits or vegetables in small ziplock baggies in the freezer that have roughly the same shape and length of your incision.

After surgery, keep the incision on ice for the first 24 hours. This will minimize swelling. After 24 hours, ice has a limited role since the swelling is essentially complete and you want to encourage blood flow to the site for healing, not restrict it.


An interesting study came out that links pain and dehydration. Another great reason to drink lots of fluids after surgery. Staying hydrated can reduce the amount of pain medications you need to take. This connection is well-known in migraine sufferers who can get relief with just some hydration and oxygen supplementation → no meds.

Dehydration is also a common cause of constipation which can cause significant abdominal pain and straining.

More and more anesthesiologists are encouraging patients to drink plenty of water before surgery, even up until 2 hours before their surgery. Historically patients have been restricted from eating or drinking anything for 8 hours before surgery. This practice may be changing and you should follow your surgeon’s recommendations. Regardless of what your surgeon tells you do, you can do a few things to make sure you are hydrated prior to surgery.

First, limit or eliminate caffeine for 2-3 days prior to surgery. Caffeine in any form has a diuretic effect, which can contribute to dehydration. Eat fruits that are mostly water and drink up until the moment that you need to stop per your surgeon’s orders.

You will receive IV fluids during your surgery and you should start drinking again as soon as you are able to after surgery. IV fluids are not superior to oral fluids. In fact excessive IV fluids have been associated with postoperative ileus (when your intestines shut down) and prolonged hospital stays*. Drinking your fluids promotes gut motility and better absorption. Remember to infuse your water with lemons and limes for intense added nutritional and health benefits.

*Hayhurst, C. & Durieux, M. (2014). Enteral hydration prior to surgery: The benefits are clear. Anesthesia & Analgesia 118(6), 1163-1164.


Yes, hydration even impacts wound healing. Injured tissue needs to be repaired by blood flow. Blood carries oxygen and essential nutrients that wounds need to heal. A lack of moisture at the wound’s surface will delay the healing process. Water is the primary way that blood gets to the wound. Dehydration is the most common way cell function gets disrupted and impaired.

Blood flow to the wound also prevents infection. White blood cells protect the body against bacteria. And water is an essential element of lymph fluid, which will remove the bacteria from the body. Lymph is an extremely important function after illness. Have you ever had a sore throat and then felt little lumps in your neck? That is lymph carrying off the infection that the body has fought off. It’s a good thing in many cases! But you lymph needs a lot of water to move the infection along. Think of that cake batter example again. By drinking, you keep the lymph thin and moving smoothly to remove the bacteria.


In severe cases like what I see in the intensive care unit, the body will literally shut down. The kidneys will stop working, the liver stops working, the gut stops working and eventually the heart and brain will stop working. After surgery fortunately, your symptoms will be much more mild.


Dry mouth


Lack of sweating

Fast heart beat

Muscle cramps

Nausea or vomiting

It may seem counter intuitive to drink fluids when you are nauseous, but it’s important. Add some ginger to water. Ginger is well-known for its anti-nausea properties and is better than many drugs on the market. So give it a try. You can even just eat the ginger by itself – though it’s a little tart. Try a ginger tea with honey. It may go down easier than a big glass of water.

More severe symptoms of dehydration include weakness, confusion and loss of consciousness. These are extreme symptoms as well a medical emergency. Your caregiver should call 911 in this case.


By the time you get home from surgery, especially same day surgery, you probably have had very little to drink. You were restricted from drinking before surgery, you had nothing during surgery except IV fluids and there is a good chance you didn’t feel like drinking much as soon as you woke up. It takes a bit of time for anesthesia to wear off and everyone responds differently.

So when you get home, your priority needs to be hydration. Drinking lots of water after surgery will help rehydrate and flush out the toxins.

A simple formula to determine how much you need is to take your weight in pounds and divide by 2. The value is the number of ounces of water you need to take in a 24 hour period for an appropriate recovery.

For instance if you weigh 160 pounds, you need to replenish with 80oz of water, which is 10 glasses of water in a 24 hour period.

Avoid sodas, caffeine and fruity drinks. Stick with the basic composition of water. You can add spices, lemons and limes, which I would encourage you to do. It not only makes the water taste better, but lemons and limes have intense healing properties and are well-known digestive aids.


How do you know when enough is enough? Like anything, you can over do it. There are cases in the literature of people who literally drink themselves to death. I mean drink so much water they die. How does that happen? Well, too much water can displace the amount of sodium and electrolytes in the body and cause dysfunction in the body. But in order to do that you literally need to drink gallons and gallons of water very quickly.

Stick to the formula above and don’t over do it. You’ll be fine. It will be hard enough to drink 10 glasses of water in 24 hours, so just strive to reach that goal.

Another way to evaluate your progress is to monitor your urine output. Dark urine means your dehydrated. Even a strong color yellow urine is consistent with dehydration. If your urine is rust color or a strong yellow, you need to keep drinking.

On the other hand if your urine looks like crystal clear water, you can slow down on the rehydration process.

Urine should be a light straw yellow color. This is the goal.

Frequency doesn’t matter as much. Everyone has a different bladder size and tolerance for fluid in the bladder. However, length of time in between when you go to the bathroom is important. If you go more than 4 hours without going to the bathroom, you need to step up your intake.

If it’s been 8 hours or more, you should call your surgeon, you may need more aggressive hydration techniques.


Drink lots of water infused with lemons or limes

Stay hydrated before and after surgery

Evaluate your progress by monitoring your urine color

Do all these things and anticipate a good recovery.