Diarrhoea vs vomiting: how the symptoms differ

Diarrhoea is frequent loose stools, while vomiting is forceful emptying of stomach contents through the mouth; either can lead to dehydration.

They can occur separately or together. Both may follow an infection, a reaction to food or medicine, or irritation of the digestive system. The practical priority is often whether you can replace the fluid and salts being lost.

Use the diarrhoea description when loose stools are the dominant change, even if nausea is present. Pay attention to whether stools are watery, contain blood or look unusually dark, and whether abdominal cramping eases after passing stool.

Sip fluids regularly and choose food only as appetite allows. A pharmacist or clinician can advise on oral rehydration products and on medicines that may be unsuitable when there is fever, blood in stool or a possible infection.

Use the vomiting description when retching or bringing up stomach contents is the main issue. Note the timing, whether vomiting follows eating, and whether small sips of fluid remain down. A short pause followed by tiny, frequent sips can be easier than drinking a full glass.

Vomiting with severe headache, a stiff neck, chest pain, significant abdominal pain or blood needs prompt medical assessment. Green vomit can also need urgent evaluation because it may signal a blockage beyond the stomach.

Fluid loss can cause thirst, a dry mouth, dizziness when standing, tiredness, reduced urination and darker urine. Babies, older adults, pregnant people and people with kidney disease, diabetes or conditions that affect immunity may need earlier advice because dehydration can become harder to manage.

Seek urgent care for fainting, confusion, inability to keep fluids down, very little urine, blood in vomit or stool, black stool, or severe and worsening pain. These warning signs matter even when the cause is not yet clear.

Nausea without vomiting, constipation, heartburn or ongoing abdominal bloating may need a different description. If pain is the main symptom, especially when it is localised, sudden or worsening, do not let the presence of diarrhoea or vomiting distract from it.

A change that begins after starting a medicine, travel, a new food, alcohol use or contact with someone who is unwell gives useful context, but it does not settle the cause on its own.

A clinician will ask which symptom started first, how it has changed, what you can drink, urine output, pain location, fever, medicines, recent travel and possible food exposures. They may examine your abdomen and look for signs of dehydration.

The next step may be home care with clear safety-net advice, a review of medicines, or tests when the pattern suggests infection, inflammation, bleeding or another digestive problem. Bring a list of medicines and describe any blood, dark stool or green vomit accurately.