What Causes Nausea?
To learn more about what causes nausea, watch The Gut Show episode above (read the episode transcript here) or continue reading!
What is nausea?
Experiencing nausea can be frustrating, because it’s hard to know what caused it and what to do about it. Depending on the severity, it can also feel like it takes over your day, leaving you feeling like you can’t give your all to anything, including work, relationships, and self care.
If you have experienced that and are looking for answers, my goal for this article is to break down the different causes of nausea so you can see what aligns best with what you’re experiencing, and then have the language to use with your providers to get better answers.
Let’s start with the definition of nausea, which is “a feeling of sickness with an inclination to vomit.” This isn’t a great definition because it’s hard to really determine what is or isn’t true nausea. It’s also tough for those experiences nausea, because the details of the symptoms can make a difference, but a “feeling of sickness” doesn’t really explain much.
Other words that may be used to describe nausea can be dizziness, extreme fatigue and lethargy, very low appetite, and increased fullness.
Symptoms that may present with nausea include:
reflux
heartburn
stomach burning
headache or migraine (which can also be linked to issues with vision).
When you’re describing nausea to a provider, it can help to write down the details you are experiencing, even if some may seem odd or insignificant. Sometimes these are the details that can help the most with understanding what’s wrong and finding solutions.
When it comes to the the bigger causes of nausea, it’s important to differentiate more acute, or short term episodes, versus chronic, or recurrent episodes over a period of time.
Acute forms of nausea can be due to sea or motion sickness, reactions to certain smells or odors, food poisoning, acute pain, acute inner ear imbalance (vertigo), or heat exhaustion or stroke.
Chronic forms of nausea can be due to anxiety, chronic pain, slowed digestion, pregnancy and hormonal changes, ongoing inner ear issues, dehydration, and medications.
When you’re trying to get to the root of nausea, it helps to think about how often the episodes occur and how long they last. Once you’ve identified that, think back to when the episodes started. What else happened around that time? Any changes that could align with the info above? And when the episodes come on, do they correlate with anything above?
With nausea, deeper causes can trigger symptoms, and there can also be other triggers that can bring on an episode or make an episode worse. I can’t go deeper into all causes of nausea, so I’ll stick to the ones I see most often in those with digestive disorders for the rest of this article.
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Anxiety
Anxiety is a major cause of nausea, and typically this is actually an anxiety symptom versus true nausea. This may also be due to changes in the vagus nerve during episodes of anxiety or stress. When the body is in a stressed state, this impacts the autonomic nervous system and that’s where the vagus nerve gets involved.
How to know if anxiety is your cause: check in on your mental health. Do you have other symptoms of anxiety, including feeling wired + tired together, being on edge and irritable, feelings of worry and lack on control, and difficulty sleeping.
If you are experiencing these signs, working with a therapist who specializes in anxiety can be helpful. They may use different therapies that can give you the tools for managing this, which will then reduce your nausea.
Pain
Pain can cause the body to release hormones like adrenaline, which activates certain receptors in the gut and brain that can result in nausea. This can be true for acute episodes or chronic episodes of pain.
How to know if pain is your cause: keep a log of your nausea and notice if it is worsened by pain or correlates to episodes of pain in any way. If you wake up in pain and also with nausea, that could be a link. Or maybe you have pain after meals, and that’s also when nausea hits.
If this is the cause for you, addressing the pain will help decrease the nausea.
Skipping meals
Your stomach produces stomach acid as part of digestion. If you are not eating for a long period of time, this can build up and lead to reflux of that acid and this will cause the symptom of nausea for some.
Also, an empty stomach and hunger can also be mistaken for nausea for some. This will be even more true if this is paired with constipation.
The tricky part with this link is that many who have nausea will skip meals because their appetite is low, so this can be a piece that continues to worsen the symptom which can send you into a spiral.
How to know if skipping meals is your cause: when nausea hits, ask yourself when you ate last. If nausea is present early in the day, or if it hits after you have gone a longer period without eating, try eating a small meal to see if it improves. If so, you’ve found a cause or contributor.
Dehydration
When you are dehydrated, your cells don’t have what they need to function and your don’t have enough fluid to send out to the body to meet its needs. This can lead to weakness, dizziness, and nausea. And this can happen even in more mild cases of dehydration (aka drinking less than you need each day).
Drinking more water when you’re currently dehydrated can also worsen nausea, so it’s important to go slow as you hydrate.
How to know if dehydration is your cause: track your water intake. If you’re drinking way less than 64 oz per day or 1/2 of your body weight (in pounds) in ounces… you may be dehydrated. Also look for other signs of dehydration including thirst, dark yellow urine, and dry skin and mouth.
Slowed digestion
When your gut motility is slowed, which can be seen with gastroparesis (slowed upper GI motility) or constipation (slowed lower GI motility), this can lead to increased nausea.
Slowed motility can also create more pressure which can cause reflux, a leading cause of nausea.
How to know if slowed motility is your cause: does it seem like food gets stuck or sits heavy in your gut after you eat? Are you pooping less than once a day or feeling backed up? Those could be signs this is a contributor, so as you work to improve motility, you should notice nausea goes down.
Upper GI issues
I’ve mentioned this a few times already, but upper GI issues can be top causes of nausea. Reflux, where contents move back into your esophagus from your stomach, can lead to nausea. This also feels like vomiting or spitting up, so that alone can trigger more nausea.
How to know if an upper GI issue is your cause: do you notice reflux happening after you eat meals or between meals? Do you have heartburn? Those can all be signs that this is a cause or contributor.
Hormonal changes
As hormones change during pregnancy, throughout the menstrual cycle, in menopause, and in conditions like hypo- or hyper-thyroidism, this can lead to more nausea.
During the menstrual cycle, nausea increases most during the pre-menstruation period, the 5-7 days leading up to menstruation, and ovulation.
How to know if hormonal changes are your cause: first evaluate any significant hormone shifts, like pregnancy and menopause, to see if those overlap with when the nausea started. Next, evaluate your menstrual cycle (if applicable). If you notice it is very irregular, speak with your doctor, as that could be the problem. If it is regular, look for correlations between pre-menstruation and ovulation with your symptoms. If they are linked, that may be your cause.
Something very wrong
When you’ve ruled out many of the common causes of nausea, but there isn’t a link or your nausea still isn’t improving, we may suspect something very wrong is happening. This can include:
Food poisoning
Infection or virus
SIBO or SIFO
Ulcer
Autoimmune disease
Thyroid disorders
Intense pain due to issues with pancreas, kidneys, gallbladder, or other organs
These connections aren’t as common, but can be present for some. This is something that would be assessed for and addressed with your trusted healthcare team.
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