Nausea and Vomiting: Causes and When to See a Doctor

Nausea is that uncomfortable feeling of needing to vomit, which sometimes leads to actually throwing up. Common causes include stomach viruses (gastroenteritis), food poisoning, pregnancy morning sickness, motion sickness, migraines, and medication side effects. While usually temporary, persistent vomiting can lead to dehydration, which may require medical treatment. Contact your provider if symptoms last more than two days or include concerning signs like blood in vomit or severe pain.

In plain words

Nausea is the feeling of needing to vomit. Vomiting is throwing up. Common causes include stomach viruses, food poisoning, pregnancy, and motion sickness. Most cases are short-term and not serious. But if you vomit a lot, you can get dehydrated. Signs of dehydration include dry mouth and feeling dizzy. See a doctor if vomiting lasts more than two days or has blood in it.

What is Nausea and Vomiting: Causes and When to See a Doctor?

Symptoms

Early symptoms

Upset stomach: A queasy or uncomfortable feeling in the stomach that often comes before vomiting. You may salivate more or feel generally unwell. (2) (5)
Loss of appetite: Not feeling hungry when you normally would. The thought or smell of food might make nausea worse. (2)
Mild sweating: Breaking out in a light sweat, especially on the forehead, often accompanies nausea. (5)
Increased saliva: Your mouth may water more than usual as your body prepares for possible vomiting. (2)
Dizziness: Feeling lightheaded, unsteady, or like you might faint, often related to motion sickness or low blood sugar. (5) (8)

Serious or emergency symptoms

Blood or coffee-ground material in vomit: Bright red blood or dark, grainy material that resembles coffee grounds can signal internal bleeding. Seek emergency care immediately. (3) (5)
Severe headache with vomiting: An extremely painful headache with vomiting, especially with stiff neck or confusion, may indicate meningitis or other serious brain condition. Go to an emergency department right away. (5)
Signs of dehydration: Dry mouth, dark urine, dizziness when standing, rapid heartbeat, and confusion can mean severe fluid loss. In infants, look for no wet diapers for 6 hours or sunken soft spots. Get medical help; may need IV fluids. (3) (1)
Severe abdominal pain: Extreme stomach pain that persists or comes in waves may indicate appendicitis, bowel obstruction, or other surgical emergency. Don't delay — go to an emergency room. (5) (3)

Causes

Primary causes

Viral gastroenteritis (stomach flu): Highly contagious viruses like norovirus cause sudden nausea, vomiting, and diarrhea. Spreads through contaminated food, surfaces, or close contact. (1) (2)
Food poisoning: Bacteria (like Salmonella) in contaminated food trigger symptoms within hours to days. Often includes fever and diarrhea. (6)
Pregnancy morning sickness: Hormonal changes cause nausea, often morning symptoms but can occur anytime. About 70% of pregnant women experience this, typically starting around week 6. (7)
Motion sickness: Discrepancy between perceived movement (like in cars, boats, or amusement park rides) and what the inner ear senses. Dizziness and cold sweats often accompany nausea. (8)
Medication side effects: Many drugs list nausea as a common side effect, including antibiotics, pain medications, antidepressants, and chemotherapy drugs. Usually temporary as body adjusts. (5)

Risk factors

Recent viral illness exposure

Being around others with stomach flu, especially in childcare or cruise ship settings, increases infection risk. (1)

Pregnancy (first trimester)

Hormonal changes make nausea very likely in early pregnancy. Some develop hyperemesis gravidarum with severe vomiting needing medical care. (7)

Prone to motion sickness

Some people are more sensitive to motion due to inner ear differences, making them more likely to feel sick in moving vehicles. (8)

Food handling without precautions

Not washing hands, undercooking meats, or leaving food at unsafe temperatures raises food poisoning risk. (6)

Diagnosis

Doctors determine the cause of nausea/vomiting by reviewing your symptoms, how long they've lasted, any patterns (like after eating certain foods), medications you take, and whether you have other symptoms like fever. They may check for dehydration signs (dry mouth, fast pulse). Physical exam focuses on abdominal tenderness. Most cases don't need testing, but severe or persistent symptoms might require blood tests, urine tests, or imaging to check for infections, blockages, or other conditions.

Medical history and physical exam

To identify possible causes based on symptom patterns, exposures, and physical signs of dehydration or abdominal issues. (4)

Blood tests

Check for infections, dehydration, electrolyte imbalances, or problems affecting liver, pancreas, or kidneys. (4)

Urine tests

Detect pregnancy, infections, or signs of dehydration that might explain persistent symptoms. (4)

Imaging (CT/X-ray/ultrasound)

Used when doctors suspect blockages, appendicitis, or other structural problems in the digestive tract. (4)

Treatment

Medication options

Antihistamines (for motion sickness)

Blocks signals from the inner ear to the vomiting center in the brain. Best taken before motion exposure. (8)

Prokinetic agents

Helps empty the stomach faster when slow digestion contributes to nausea, such as with migraines or gastroparesis. (5)

Serotonin blockers

Interferes with serotonin signals that trigger nausea/vomiting, often used for chemo, radiation, or surgery-related nausea. (5)

Lifestyle and self-care

Hydration strategy: Sip small amounts (1-2 oz every 15 minutes) of clear fluids like water, diluted juice, broth, or oral rehydration solutions once vomiting slows. Wait 30-60 minutes after vomiting before trying fluids to avoid triggering more vomiting. (3)
Diet adjustments: After vomiting stops, start with bland foods like crackers, toast, or rice. Avoid dairy, fatty, spicy, or very sweet foods until fully recovered. The BRAT diet (bananas, rice, applesauce, toast) can help ease back into eating. (3) (2)
Positioning: Sit upright for meals and remain upright for 30 minutes after eating. Sleeping with head elevated helps some with nighttime nausea. Avoid lying flat which can worsen stomach discomfort. (2)
Environmental controls: Avoid strong food smells, cooking odors, perfume, or smoke. Fresh air may help. Cool compresses on the forehead sometimes relieve nausea sensations. (2)

Always discuss dosing and treatment changes with your own prescriber.

Possible complications

Dehydration: Repeated vomiting leads to fluid and electrolyte loss. Severe dehydration can cause low blood pressure, kidney problems, or even shock without treatment. (3) (1)
Aspiration: Vomit entering the lungs can cause pneumonia. This is particularly risky in young children, older adults, or those with impaired consciousness. (5)
Electrolyte imbalances: Loss of salts like potassium and sodium affects heart rhythms and nerve/muscle function. May show as muscle cramps, weakness, or irregular heartbeat. (5)
Mallory-Weiss tear: Severe vomiting can cause small tears at the esophagus-stomach junction, sometimes leading to bleeding. Usually heals on its own but may require medical attention. (5)

When to see a doctor

Routine follow-up

Schedule a visit if nausea lasts more than 2 days (1 day for children under 2 or adults over 65) or keeps returning. Also see your provider for pregnancy-related vomiting that prevents keeping food down or causes weight loss. (2) (5)
Discuss persistent medication-related nausea with your prescriber before stopping treatment. There may be alternatives or strategies to reduce this side effect. (5)

Seek emergency care

Go to the emergency room for vomiting with severe headache/stiff neck (possible meningitis), chest pain, bloody vomit, severe abdominal pain, or signs of dehydration like rapid heartbeat and confusion. (3) (5)
Call emergency services for head injury followed by vomiting (concern for brain injury) or suspected poisoning ingestion that triggered vomiting. Don't delay with these situations. (3) (5)

Frequently asked questions

Why do I feel nauseous but not vomit?

Nausea doesn't always lead to vomiting. Your stomach may feel queasy without emptying its contents. Possible causes include stress, mild stomach irritation, early infections, or motion sensitivity without severe stimulation. If persistent, check with a doctor to identify possible causes like gastritis, acid reflux, or medication effects. (2) (5)

Can dehydration cause nausea?

Yes — dehydration often worsens nausea, creating a cycle where vomiting leads to more fluid loss. Early dehydration signs are thirst, dry mouth, and dark urine. That's why small, frequent sips (even if vomited back up for a time) are crucial to break this cycle. (3) (1)

What foods help stop nausea?

Ginger in tea, candies, or capsules helps some people. Small bland foods like crackers or toast often settle stomachs once vomiting stops. Cold foods (like popsicles) or carbonated drinks may be better tolerated than hot meals. Avoid large portions, fatty foods, or strong flavors until feeling better. (2)

Why do I wake up nauseous?

Morning nausea has several possible causes: pregnancy (especially first trimester), acid reflux (often worsened by lying flat), empty stomach (low blood sugar), medication side effects (check timing of new pills), or migraines (which often begin upon waking). If persistent, discuss patterns with your provider to identify causes. (7) (5)

Can anxiety make you vomit?

Yes — intense anxiety triggers the body's fight-flight response, which can upset digestion. Panic attacks often include nausea; some people do vomit from overwhelming stress. Deep breathing, distraction, and addressing sources of anxiety help, but recurrent anxiety-driven nausea may benefit from counseling or medical treatment. (5)

References

CDC — Viral Gastroenteritis ('Stomach Flu') source 1
NHS — Feeling sick (nausea) source 2
NHS — Vomiting in adults source 3
MedlinePlus — Nausea and vomiting source 4
Mayo Clinic — Nausea and vomiting source 5
CDC — Foodborne Germs and Illnesses source 6
NHS — Severe vomiting in pregnancy source 7
MedlinePlus — Motion sickness source 8