Butterflies in your stomach? What nerves do to your body

Why do you get butterflies in your stomach before something big?

Because your body thinks something important is about to happen, and it’s getting you ready. When you’re nervous, your brain sets off the stress response, often called fight or flight. Harvard Health explains that your adrenal glands start “pumping the hormone epinephrine (also known as adrenaline) into the bloodstream”.

Adrenaline moves your body’s resources toward action. Cleveland Clinic lists what it does: your heart beats faster, you breathe faster, and “your digestion slows so other muscles can use the blood that digestive organs would normally use”. That shift is a big part of the fluttery, hollow feeling in your stomach.

Your gut is also wired closely to your brain. “The gastrointestinal tract is sensitive to emotion,” Harvard Health says, and stress “can affect movement and contractions of the GI tract.” So a nervous stomach isn’t in your head. It’s real, and it has a reason.

What else do nerves do to your body?

Butterflies rarely arrive alone. Here are the most common things people feel before a big day, what’s behind each one and one small thing to try.

What you feel	What’s happening	One small thing that helps
Butterflies or a knotted stomach	Adrenaline slows digestion	A few slow breaths out, and don’t skip your usual meal
Racing or pounding heart	Your heart speeds up to send blood to your muscles	Breathe out for longer than you breathe in
Faster breathing	Your body takes in more air, ready for action	Slow it down on purpose with a belly breath
Sweaty palms	Sweat glands switch on when you’re nervous	Keep a tissue in your pocket and let it be
Shaky hands	Stress, fear and caffeine can make normal shaking stronger	Skip the extra coffee and breathe out slowly
Dry mouth	Feeling stressed or anxious can dry your mouth	Bring water, or chew sugar free gum
Needing the bathroom	Stress can upset your stomach and bowels	Go before you leave, and go easy on coffee

A few notes on where these come from. Cleveland Clinic says the body’s sweating “activates when you exercise or if you’re nervous”. MedlinePlus, from the US National Library of Medicine, says “everyone has some tremor when they move their hands”, and that stress, fear and caffeine may make it stronger. It also says you “can also get dry mouth if you feel stressed or anxious”, and suggests drinking water or chewing sugar free gum. MedlinePlus lists an upset stomach and diarrhea among the signs of too much stress, and it calls caffeine “a diuretic”, meaning it makes you pee more. That’s one more reason to skip the extra coffee on a big morning.

None of these mean something is wrong. They mean your body is turning the volume up.

Why does your mind go blank when you’re nervous?

That blank moment is one of the most frustrating parts of nerves. You know the answer, the first line, the next step, and then it’s gone.

Stress hormones may be part of the reason. In a small 2000 study, people given a stress hormone an hour before a memory test recalled fewer of the words they’d learned the day before. The study suggests the problem was reaching the memories, not having learned them.

So plan for the blank instead of fearing it. Write your first line, or your first step, on a card or your phone. If your mind empties, pause, breathe out slowly and look at it. Then carry on from there. Our guide on how to calm nerves before a presentation has more on what to do when your mind goes blank mid-talk.

Is it normal, and does the feeling pass?

Yes, and yes. Feeling nervous before something that matters is a normal reaction, not a warning sign. MedlinePlus puts it plainly: “In short bursts, stress can be positive, such as when it helps you avoid danger or meet a deadline.”

The stress response is built to switch off, too. Harvard Health says “when the threat passes, cortisol levels fall”, and your body’s “rest and digest” side calms things down again. Cleveland Clinic describes the same thing: your parasympathetic nervous system “steps in and returns things to normal”.

Many people find the waiting room harder than the moment itself. Once you’ve started talking, driving or answering, there’s something to do with all that energy.

What helps your body settle before a big day?

You can’t switch nerves off, and you don’t need to. These small things help your body come down a notch.

1. Make the breath out longer. In a 2023 study, five minutes a day of cyclic sighing (a slow breath in, a second short breath in on top, then a long, slow breath out) improved mood more than the same time of mindfulness meditation. It’s an easy one to do in a hallway.
2. Try a belly breath. Cleveland Clinic’s diaphragmatic breathing slows your breathing rate and lists “helping you relax” among its benefits. Rest one hand on your chest and one on your belly, breathe in so the belly rises, and breathe out gently.
3. Tell yourself your body is getting ready. In one study, people who were taught to see their body’s stress response as useful before a stressful speech showed “more adaptive cardiovascular stress responses” than those who weren’t. It’s a simple sentence: “this is my body getting ready.”
4. Don’t skip meals. Harvard Health warns that skipping meals can cause “drops in blood sugar that cause you to feel jittery”. Eat something you normally eat and know your stomach is fine with.
5. Go easy on caffeine. MedlinePlus lists “restlessness and shakiness”, a fast heart rate and anxiety among the effects of too much caffeine. On a nervous morning, skip the extra cup.
6. Keep water close. It helps with a dry mouth, and it gives your hands something to do.

For a wider plan for the night before and the morning of, see our guide on how to calm nerves before a big day.

How can ikuyo help when your nerves show up in your body?

Knowing why your body does this is a good start. Practicing what helps, before you need it, is where ikuyo comes in.

You tell Scout, ikuyo’s small explorer robot, what’s coming up. Scout turns the days before into a map of short quests, like a paced breath you can replay as often as you like, and keeps you company on the day itself. It’s free to start. If your butterflies come before a talk, a toast or a presentation, our mission for public speaking anxiety is the place to start.

ikuyo is a companion for the days before something big. It isn’t therapy or treatment.

When should you see a doctor?

Most nervous symptoms fade once the moment has passed. Some signs should never be put down to nerves, though.

Get emergency help (call 911 in the US, or your local emergency number) if you have chest pain or trouble breathing, or if you faint. MedlinePlus lists these among the reasons to get emergency help with a racing heart. Don’t wait to see if it’s nerves.

Talk to your doctor if your symptoms don’t settle after the event, if they keep coming back, or if they’re new or different from usual. MedlinePlus also suggests contacting your health care provider “if you feel overwhelmed by stress, or if it is affecting your health”. Asking is always a sensible step.

If you ever feel unsafe or overwhelmed, you don’t have to wait. Our help now page lists people you can talk to right away.