Nausea (Feeling Sick): Causes and Relief

Why you feel nauseous

Nausea is controlled by a region in the brainstem called the vomiting center. It receives signals from the gut, the balance system in the inner ear, a chemical sensor that detects toxins and drugs in the blood, and higher brain areas involved in emotion, smell and memory. That is why so many different things, from a virus to a bad smell or fear, can make you feel sick.

Common causes of nausea

Stomach and gut

• Gastroenteritis (stomach bug) and food poisoning: sudden nausea, vomiting and diarrhea, often with cramps. Usually better in 1 to 3 days.
• Indigestion and reflux: nausea with burning, bloating and fullness after meals. See GERD.
• Gastritis and ulcers, often from NSAIDs or alcohol.
• Constipation.
• Gallstones: nausea with pain under the right ribs after fatty meals.
• Gastroparesis: slow stomach emptying, common in diabetes, causing early fullness and vomiting of undigested food.

Pregnancy

Nausea affects up to 80% of pregnant people, usually from about week 6 to week 12 to 16. Despite the name morning sickness, it can happen at any time of day. Severe, persistent vomiting with weight loss is hyperemesis gravidarum and needs treatment.

Inner ear and motion

Motion sickness, vertigo, labyrinthitis and Ménière's disease cause nausea through the balance system. Nausea that comes with a spinning sensation points here.

Brain and nervous system

• Migraine: nausea is very common during attacks, with light and sound sensitivity.
• Anxiety and stress: "butterflies", nausea before events, or nausea with panic.
• Concussion or head injury.
• Raised pressure in the brain and meningitis, which are emergencies.

Medicines and substances

Common culprits include antibiotics, opioids, chemotherapy, iron and potassium supplements, metformin, GLP-1 medicines for diabetes and weight loss (semaglutide, tirzepatide), NSAIDs, hormonal birth control and digoxin. Alcohol and hangovers, cannabis (cannabinoid hyperemesis syndrome) and smoking also cause nausea.

Other medical causes

• Heart attack, especially in women, older adults and people with diabetes
• Infections with fever, such as flu, COVID-19 and urinary or kidney infections
• Diabetic ketoacidosis and very high or low blood sugar
• Kidney or liver failure, hepatitis
• Low sodium, high calcium and thyroid problems
• Appendicitis, pancreatitis and bowel obstruction

Feeling sick with a hot, red, sweaty face

Feeling hot, flushed and sweaty with an upset stomach is a common combination. It usually happens because the same nerve response (the vagus nerve and adrenaline) that causes nausea also triggers sweating and flushing. Common explanations:

• the start of a stomach bug or other infection, before a fever is measured
• just before vomiting, when sweating and flushing often peak
• heat exhaustion after time in hot weather or exercise, with heavy sweating, headache and weakness
• anxiety or a panic attack
• alcohol flushing, menopause hot flashes or a reaction to food or medicine

Check your temperature. Get urgent help if there is confusion, fainting, very hot dry skin, chest pain or a stiff neck. If it follows heat exposure, move somewhere cool, sip water and loosen clothing.

Nausea with side pain

An ache in your side with nausea may come from a kidney stone (waves of severe pain from back to groin), a kidney infection (fever, burning urination), gallbladder pain (upper right), appendicitis (lower right) or trapped gas. See sharp abdominal pain and flank pain.

How doctors find the cause

A doctor will ask when the nausea started, whether you are vomiting, what you have eaten, medicines, the possibility of pregnancy, and other symptoms such as pain, headache, fever or dizziness. Tests depend on the clues and can include a pregnancy test, blood tests for kidney, liver, sugar and electrolytes, urine tests, an ECG, and an ultrasound, endoscopy or scan for persistent symptoms.

What helps nausea

Home remedies

• Sip clear fluids often: water, oral rehydration solution, weak tea or diluted juice. Small sips every few minutes are better tolerated than large drinks.
• Eat small, bland meals when you can: crackers, toast, rice, bananas. Avoid greasy, spicy and very sweet foods.
• Get fresh air and avoid strong smells.
• Ginger in tea, candies or capsules has good evidence for pregnancy and motion sickness.
• Acupressure wristbands on the P6 point help some people.
• Rest sitting upright after eating rather than lying flat.

Medicines

• Motion sickness: meclizine or dimenhydrinate, taken before travel. They cause drowsiness.
• Bismuth subsalicylate for an upset stomach. Not for children or teenagers, pregnant people, or people allergic to aspirin.
• Antacids for nausea with indigestion.
• Pregnancy: vitamin B6, with or without doxylamine; ask your prenatal provider.
• Prescription anti-nausea medicines such as ondansetron are used for severe vomiting, chemotherapy and after surgery.

Follow the label dose on all over-the-counter medicines.

Frequently asked questions

What does it mean if I feel very hot, have a red face, am sweating and have an upset stomach?

Most often it is the body's nerve response just before vomiting, the start of an infection, heat exhaustion, or anxiety. Check for fever, cool down and sip fluids. Seek urgent care if there is confusion, fainting, chest pain, very hot dry skin or a stiff neck.

Why do I feel sick all the time?

Constant nausea can come from reflux, gastritis, medicines, pregnancy, anxiety, migraine, gastroparesis, cannabis use or, less often, liver, kidney or thyroid problems. Nausea lasting more than a week, or with weight loss, should be checked by a doctor.

What is the fastest way to get rid of nausea?

Sit upright, breathe slowly, get fresh air and sip cold water or ginger tea. Avoid food smells and lying flat. Over-the-counter remedies help for motion sickness or indigestion. Nausea with severe pain, fever or dehydration needs medical care.

Can anxiety cause nausea?

Yes. Anxiety activates the stress response, which slows digestion and stimulates nerves linked to the vomiting center. Nausea is common before stressful events and during panic attacks. Breathing exercises and treating the anxiety usually help.

When is nausea a sign of something serious?

Nausea is more likely to be serious if it comes with chest pain, severe belly pain, a severe headache or stiff neck, confusion, vomiting blood, signs of dehydration, or after a head injury. Get emergency help in these situations.