Can Anxiety Cause Nausea? Unpacking the Gut-Brain Connection

Why Taking Care of Your Gut Is Critical if You Suffer From Anxiety

• Can Anxiety Cause Nausea?|
• Unpacking the Gut-Brain Connection|
• Address Anxiety Symptoms Through the Gut |
• Signs and Symptoms of Anxiety|
• Your Mental Health|

One of my favorite descriptions of anxiety is a “fear of what could happen in the future.” While it’s not a universal definition, it certainly simplifies a complex psychiatric disorder into something we can all understand, and, at least to some degree, relate to. 

You might be surprised to hear that there’s a direct connection between what goes on in your brain and what happens in your gut. Interestingly, the communication pathways are a two-way street. Information flows from the brain to the gut as well as from the gut to the brain. Understanding this connection may help you make sense of the physical symptoms of your anxiety and help equip you to better deal with them. But can anxiety cause nausea?

The answer is likely yes, along with other digestive symptoms that include stomach cramps, constipation, and diarrhea [1, 2, 3]. If you’ve ever experienced “butterflies” in your stomach before a big performance (known as performance anxiety), you’ve experienced how intense emotions or other psychological phenomena can affect your digestive system. This effect is actually part of a well-studied field of research regarding the gut-brain connection, which also helps explain why those with gut disorders are more likely to experience anxiety.

While everyone deals with situational anxiety from time to time — feeling anxious about tomorrow’s work presentation, or because your teenager is about to go off to college — chronic anxiety can lead to cognitive and physical symptoms. These long-term symptoms can adversely affect your life, especially if you don’t have the tools to deal with them.

How you treat your body (through diet and lifestyle) can have an effect on your anxiety levels just as much as a calming technique like deep breathing can have an effect in your digestive system. Let’s do a brief overview of the signs and symptoms of anxiety, the details of how anxiety can cause nausea, and unpack the gut-brain connection to discover what you can do to improve your anxiety symptoms.

Can Anxiety Cause Nausea?

In short, the answer to the question “Can anxiety cause nausea?” is yes. A 2002 literature review looking at the psychophysiology of nausea found that nausea is commonly felt in anxiety-provoking circumstances, such as just before giving a speech or performing in front of an audience [2].

During the fight or flight response (a chemical response that engages while experiencing stress and anxiety), your body ceases to put energy into the function of your digestive system. Instead, it sends blood out to your limbs to prepare you to run or fight to defend yourself. In such threatening situations, your sympathetic nervous system activity increases and parasympathetic activity decreases, both of which cause digestive activity to slow down or stop. This can cause you to experience nausea during the stress response, which is frequently activated by anxiety and anxiety disorders [2].

Unpacking the Gut-Brain Connection

You may notice that when you slow down and focus on your physical health (regular exercise, a healthy diet, and good sleep hygiene), mental health, and overall wellness, your feelings of nausea may go away. The gut-brain connection helps explain this phenomenon.

Rigorous research shows a connection between gut disorders and anxiety. A wide array of meta-analyses and systematic reviews (which offer the highest quality of evidence) and individual observational studies have found that anxiety often co-occurs with gastrointestinal disorders, including:

• Irritable bowel syndrome (IBS) [4, 5, 6, 7]
• Inflammatory bowel disease (IBD) [6, 8]
• Celiac disease (an autoimmune response to gluten) [9, 10]

These studies also showed that anxiety is more prevalent in people with these gut disorders than in people without them. Unfortunately, the correlative relationship between anxiety and gut disorders is unclear — we don’t know if anxiety causes digestive disorders or vice versa. And we don’t know if the two often occur together for a third, unknown reason [11, 12].

That being said, it’s safe to say that people with gut dysfunction are more likely than healthy people to have anxiety [13]. Even more, this anxiety can actually increase their perception of their chronic health symptoms, including nausea.

How to Address Anxiety Symptoms Through the Gut

Our clinical experience, in addition to randomized controlled trials, points to a reduction in anxiety symptoms with consistent probiotic use. While more work needs to be done to establish a causal relationship between gut health improvement and mental health improvement, this is a promising start [14].

While the below gut-healing therapies often help alleviate the physical symptoms of anxiety, you may need additional support. Breathing exercises, cognitive behavioral therapy (CBT), and even talk therapy can help reduce signs and symptoms of anxiety [15].

Probiotics to Improve Gut Health and Anxiety Symptoms

Probiotics contain beneficial bacteria and fungi that fortify the large intestine to help digest complex fibers and keep the gut lining sealed. The standard American diet doesn’t provide adequate quantities of fermented foods that contain probiotics, so unless you’re making a concerted effort to add these foods in, supplementing is important to ensure proper gut health and the integrity of the gut lining.

Probiotics also have an anti-inflammatory effect and have been shown to reduce inflammatory symptoms in patients with IBS, ulcerative colitis, and IBD. Studies show that probiotics and other gut-focused therapies can help to improve symptoms of anxiety. 

Two strong meta-analyses of randomized controlled trials found that probiotics appeared to improve anxiety symptoms, especially in clinically anxious people [14, 16]. Four additional systematic reviews of the same rigor showed that probiotics may exert some anti-anxiety effects, but the data were inconclusive [14, 17, 18, 19]. However, another study found that while probiotics are beneficial for treating anxiety, dietary changes were likely more helpful [20].

One possible explanation for the benefits that resulted from these studies is the positive effect probiotics have on leaky gut syndrome [21]. Intestinal permeability allows bacterial toxins to leak into the bloodstream and contribute to anxiety, and probiotics help plug the leak [22].

Probiotics have shown to be safe and have numerous health benefits, so it’s likely worth giving them a shot to improve any anxiety-related nausea.

Diet Changes and Herbs to Reduce Anxiety Symptoms

Since we know that gut health and mental health are intimately connected, it stands to reason that diet improvements and beneficial herbs may help alongside a good probiotic supplement. 

Interestingly, a systematic review of randomized controlled trials found that improving the diet may reduce anxiety symptoms in women but not men [23]. The explanation as to why wasn’t suggested in the review, but other research does point to a more gender-neutral efficacy among other diet-based interventions — including the low FODMAP diet, which restricts certain types of carbohydrates temporarily [20].

The idea behind this specific diet is to reduce the food source for harmful bacteria residing in the small intestine, lower gut inflammation, and provide a reset for the gut lining to heal and seal.

Still another systematic review of observational studies found that vegan/vegetarian diets may generally reduce anxiety scores, despite findings that vegans/vegetarians under the age of 26 may have a higher risk of anxiety [24]. A possible explanation of these mixed results is that an imbalanced vegan diet can lead to a deficiency of important B vitamins, contributing to anxiety symptoms. 

We know that a good-quality, nutrient-dense approach to plant-based eating can have an anti-inflammatory, alkalizing effect on the body, so it may stand to bolster the potential link between mental health and inflammation. Before embarking on the low FODMAP diet, start with a simple Paleo diet to reduce inflammation. I always recommend starting with the least-restrictive approach first, and then slowly narrowing if you don’t see improvements.

On the herbal supplement side of things, those with a reputation for their calming and relaxing effects seem to hold up against scientific scrutiny. A systematic review of 100 randomized controlled trials found that lavender, passionflower, saffron, black cohosh, chamomile, and chasteberry may help mitigate anxiety without negative side effects [25]. By reducing your anxiety with these supplements, they may help get any anxiety-induced nausea under control.

Having herbal options to help support the effects of other gut-healing improvements like physical activity, better sleep, and other relaxation techniques can serve to potentially reduce the need for pharmaceutical intervention.

Commonly used anti-anxiety medications like benzodiazepines are extremely habit-forming, and SSRIs (antidepressants) and other psychiatric meds come with their own lists of side effects, so herbal options could be a great place to start. This isn’t to say that every person with clinical anxiety won’t require pharmaceutical support, but it’s great to have other, natural options.

Other Signs and Symptoms of Anxiety

Knowing the possible symptoms of anxiety can help you identify a pattern in yourself that you may not realize requires attention. Many people live with anxiety for years without recognizing that they have a problem or fully grasping the toll it takes on their daily lives. 

Importantly, if you’ve received an anxiety disorder diagnosis, you’re not alone. Anxiety is among the most common psychiatric disorders in the general population [1]. About 12% of people have specific phobias, such as agoraphobia (fear of crowded spaces or of leaving the house), which affects about 2.5% of people (1). Another type of anxiety, social anxiety disorder, impacts nearly 7% of people.

Anxiety symptoms can include cognitive, behavioral, emotional, and physical symptoms, as follows.

Cognitive symptoms are those that affect your thoughts and ability to process information. They can affect your productivity at work, your ability to adequately or accurately assess life situations, and can affect judgment. Some examples include [1]:

• Fear of losing control, physical injury, death, going crazy, or negative judgment from others
• Frightening thoughts, mental images, or memories
• Derealization (perception that your surroundings aren’t real) or depersonalization (feeling that your thoughts and feelings don’t belong to you; loss of identity)
• Poor concentration, confusion, distractibility
• Narrowed attention, hypervigilance
• Poor memory
• Difficulty speaking

Behavioral anxiety symptoms are less about conscious decision-making and more about unconscious or instinctive reactions. These may include [1]:

• Avoiding real or imagined threats
• Escapism or flight
• Seeking safety and reassurance
• Restlessness, agitation, or pacing
• Hyperventilation (super-fast breathing — aka overbreathing — that causes you to lose too much carbon dioxide and become lightheaded and dizzy)
• Freezing or motionlessness
• Trouble speaking

Affective (emotional) symptoms are the feelings that may trigger behavioral reactions, such as nervousness and fear. These emotions can be overpowering and result in detrimental effects at work and in life, especially if they’re so intense that they paralyze you into inaction. Some examples are :

• Feeling nervous, tense, or wound up
• Feeling frightened, fearful, or terrified
• Feeling edgy, jumpy, jittery
• Feeling impatient or frustrated

Physical anxiety symptoms often target the digestive tract, potentially causing nausea, stomachache (or stomach cramps), and diarrhea. Some other examples include [1]:

• Rapid heart rate or palpitations
• Breathlessness or rapid breathing patterns
• Chest pain or chest tightness
• Sensation of choking
• Shortness of breath (dyspnea) not related to effort, lung function diseases (like chronic obstructive pulmonary disease/COPD or lung cancer), or occasional sighs/yawns to fill the lungs [26]
• Dizziness or lightheadedness
• Sweating, hot flashes, or chills
• Trembling or shaking
• Tingling or numbness in the arms and legs
• Weakness, unsteadiness, or faintness
• Muscle tension or feeling generally rigid
• Dry mouth

While the list of signs and symptoms is long, individual people experience anxiety in a variety of different ways. In fact, you likely won’t check every box on this list, even if you suffer from severe or chronic anxiety. We’re all built a little differently.

Many of these symptoms may not register as signs of anxiety when viewed in isolation, so it’s important to know how this list lines up with your own patterns and symptoms to understand how and whether you’re experiencing anxiety. In other words, you don’t need to experience a full-on panic attack to be suffering from anxiety. Panic disorder is only one type of anxiety disorder. There are nine in total, including generalized anxiety disorder, and many people experience anxiety without panic attacks [1, 27].

Your Mental Health

Taking care of your mental health is just as vital as taking care of your physical health. In the case of the question “Can anxiety cause nausea?” the mental and physical aspects of health intersect. Anxiety can cause nausea, and the gut-brain connection helps explain why this is the case.

It’s important to understand the most common symptoms of anxiety so you can determine whether you may have an undiagnosed condition. Anxiety that manifests as an upset stomach can severely affect your quality of life, so getting the help you need from a healthcare professional or mental health professional is vital. We’d love to help. Reach out to our clinic to set up a time to connect.

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