A COVID Vaccine Pro-Tip: Stay Hydrated Before & After

Now you have an excuse to buy that comically oversized water bottle.

by JR Thorpe
A young latin woman wearing sports clothes at home and drinking water from a reusable bottle after a...
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You’ve got your COVID shot appointment, you’ve lined up your best getting-the-vaccine outfit, and you’re all ready with mask and hand sanitizer. Did you put a giant reusable water bottle on your pre-vax list? Even if you don’t tend to feel lightheaded or faint after getting shots, bringing water, and making sure you’re drinking loads before and after, should be one of your appointment essentials. Experts tell Bustle that focusing on your hydration can reduce the side effects of your COVID vaccination.

“It’s extremely important to ensure you’re hydrated prior to and post-vaccination,” Dr. Robert Quigley M.D., global medical director at medical and security risk mitigation company International SOS, tells Bustle. The most common side effects from the three COVID vaccines, according to the Centers for Disease Control & Prevention (CDC), are pain, fatigue, headache, fatigue, and muscle pain, and experts say hydration can help to relieve them all. Being properly hydrated won’t stop you from feeling poorly post vax, but it might shorten the length of your side effects or affect how intense they are.

Why Hydration Can Help COVID Vaccine Side Effects

“The COVID vaccine and all vaccines work by activating your immune system to generate antibodies to an infectious disease, without being exposed to the virus or bacteria,” Dr. Sachin Nagrani M.D., medical director of healthcare company Heal, tells Bustle. Having good circulation is important to your immune system and its vaccine response, as healthy bloodflow carries immune cells around the body, to and from the locations where they’re needed.

When you get a COVID vaccine, your immune system reacts with a flood of new antibodies, which is what lies behind side effects like fevers, chills, and fatigue. Hydrating well pre- and post-COVID vaccine, Dr. Nagrani says, means your circulatory system can get to work, spreading these fresh antibodies to all your organs and carrying away any waste materials created by immune cells. The better hydrated you are, the more efficient it will be, and the sooner your side effects might ease.

Why Dehydration Might Make COVID Vaccine Side Effects Worse

“Inadequate hydration or, even worse, dehydration, can exacerbate the side effects of the vaccine,” Dr. Quigley says. This is partly because you’re more vulnerable to fatigue and headaches when you’re dehydrated, and partly because the circulatory system won’t function as effectively. That’s also why you shouldn’t drink alcohol before or after your vaccinations: the dehydration will likely make any side effects even more unpleasant.

“A fairly common side effect after getting vaccinated is developing a fever, which can lead to fluid loss and dehydration via sweating,” internal medicine physician Dr. Vivek Cherian M.D. tells Bustle. That can cause headaches, chills, and fatigue on its own. Staying on top of your hydration with lots of water, even if you just want to curl up under the covers, will help you endure having a temperature without having to cope with dehydration-related symptoms, too. Nausea is a side effect of COVID vaccines too, and that’s a quick route to fluid loss, so sipping water in small amounts can reduce the urge to hurl. On top of staying hydrated, you can also take a non-anti-inflammatory pain reliever like acetominophen if you’re uncomfortable post-vaccine.

If you don’t get any side effects — and they’re not guaranteed — it doesn’t mean that your COVID vaccine isn’t working effectively. But if the shivers, chills, a crushing sense of fatigue, or annoying pain at your injection site do pop up, keep drinking water; it’ll help them pass sooner rather than later.


Dr. Vivek Cherian M.D.

Dr. Sarin Nagrani M.D.

Dr. Robert Quigley M.D.