Food Poisoning: Symptoms, Causes & Treatment Options

Food poisoning can leave you feeling miserable and drained, especially when nausea, vomiting, or diarrhoea comes on suddenly after a meal. 

It happens when food or drinks are contaminated with harmful germs or toxins, and while most cases settle within a few days with rest and fluids, some situations do need medical attention.

If you are dealing with stomach cramps, repeated vomiting, or diarrhoea, it is natural to have questions: How long will this last? Is it something you can manage at home? Should you see a doctor? 

Understanding what to look out for can help you decide the next steps with greater confidence.

What is food poisoning?

Food poisoning happens when you eat or drink something contaminated with harmful germs or toxins. Your digestive system reacts to protect you, causing uncomfortable symptoms like nausea, vomiting, and diarrhoea. While it feels miserable, most cases clear up on their own within a few days.

What causes food poisoning?

Understanding what's making you sick can help you know what to expect. Many different germs and toxins can contaminate your food.

High-risk foods

Knowing which foods pose the most risk can help you stay safer:

• Animal products:

  • Raw fish (like sushi) and undercooked meat

  • Raw milk and unpasteurised dairy products

  • Raw eggs and foods containing them

• Fresh produce:

  • Unwashed fruits and vegetables

  • Pre-prepared salads and sandwiches

Cross-contamination happens when raw foods touch ready-to-eat items. Poor food handling practices at restaurants or at home may increase your risk.

Common bacteria

Bacteria are the most frequent cause of food poisoning. Here are the main types:

• Salmonella:

  • Lives in raw eggs, poultry and meat

  • Causes fever, diarrhoea and stomach cramps that start 6 to 72 hours after eating

• E. coli:

  • Most strains cause mild illness that passes quickly. Some require closer monitoring.

  • In rare cases, certain types can damage your kidneys

• Campylobacter:

  • Contaminates raw poultry and unpasteurised milk

  • One of the most common causes of diarrhoea worldwide

• Listeria:

  • Grows even in cold temperatures, making refrigerated foods risky if contaminated

  • Pregnant women and people with weak immune systems should watch for symptoms more carefully

Bacterial food poisoning often develops within 6 to 72 hours after eating contaminated food. Most bacterial infections clear up on their own. You may need antibiotics or medical monitoring to prevent complications.

Viruses

Viruses spread easily and cause many outbreaks. The two main types for you to watch for:

• Norovirus:

  • Highly contagious

  • Spreads through contaminated food, water, or surfaces

  • Symptoms start suddenly and include violent vomiting and diarrhoea

• Hepatitis A:

  • Spreads through contaminated food and water

  • More common in areas with poor sanitation

  • Affects your liver and can make you ill for weeks

Viral food poisoning doesn't respond to antibiotics. It usually gets better on its own within a few days.

Parasites and toxins

Parasites take longer to cause symptoms and can be trickier to diagnose. Some common sources include:

• Giardia:

  • Lives in contaminated water

  • Causes persistent diarrhoea and bloating

• Toxoplasma:

  • Comes from undercooked meat and cat faeces

  • Needs particular attention during pregnancy

• Natural toxins:

  • Certain tropical fish contain toxins that affect your nervous system

  • Mushroom toxins can be very serious

If your symptoms last more than a week or you've recently travelled abroad, parasites might be the cause. You'll need specific testing.

Recognising your symptoms when food poisoning strikes helps you understand what's happening in your body and when you might need extra support.

What are the common symptoms of food poisoning?

Your body reacts to contaminated food in recognisable ways. You'll often notice the first signs within hours of eating contaminated food, though sometimes they can take days to appear.

Symptoms of food poisoning include:

• Nausea and vomiting

• Diarrhoea or watery stools

• Stomach cramps and pain

• Fever and chills

• Weakness and fatigue

• Loss of appetite

• Bloating and upset stomach

Most people feel quite unwell but start improving within 24 to 48 hours. Some germs make you sick within an hour, while others take several days.

The timing and pattern of your symptoms can help you and your doctor identify what's causing your illness, whether it's food poisoning, a stomach virus, or something else.  This knowledge helps determine the best approach to your care and when you need medical attention.

When do you need medical attention?

Most people recover at home without complications. Some warning signs mean you should seek help.

Watch for signs of severe dehydration

Dehydration can become serious quickly. When you're vomiting and experiencing diarrhoea, your body loses essential fluids and electrolytes faster than you can replace them. Without these, your organs can't function properly, and in severe cases, this can lead to kidney problems, shock, or other complications.

You may notice these warning signs:

• Extreme thirst

• Dark yellow or brown urine, or not urinating for several hours

• Dizziness when standing

• Dry mouth and cracked lips

• Sunken eyes

• Confusion or irritability

• Rapid heartbeat

If you notice any of these dehydration symptoms alongside other concerning signs, it's important to seek medical attention promptly.

When to visit an Urgent Care Centre

Urgent Care Centres (UCCs) are ideal for food poisoning cases that need medical attention but aren't immediately life-threatening. They can provide IV fluids, assess your condition, and determine whether you need further care. 

Contact your doctor or go to a UCC if you have:

• Diarrhoea lasting more than 3 days

• Bloody or black stools

• Ongoing vomiting that stops you keeping fluids down

• Fever above 38.5°C

• Severe headache with neck stiffness

• Blurred vision or muscle weakness

• Symptoms that get worse instead of better

When to go to the emergency room

Emergency rooms are reserved for critical, potentially life-threatening situations that require immediate intervention.

Go to the emergency room immediately if you have:

• Blood in your vomit or severe abdominal pain

• Signs of severe dehydration and you can't drink

• Loss of consciousness

• Difficulty breathing or swallowing

• Severe muscle weakness or paralysis

These emergency symptoms suggest complications that could be dangerous without immediate treatment. While most food poisoning resolves on its own, these warning signs mean your body needs urgent medical support.

It's completely normal to feel uncertain about whether your symptoms warrant medical attention. If you're pregnant, caring for a baby with food poisoning, older, or have a weakened immune system, contact your doctor sooner. Your body (or your baby's body) handles infections differently. Getting early advice gives you better outcomes.

How is food poisoning treated? 

Your treatment depends on how severe your illness is. Most people recover with simple care at home. 

Home care for mild cases

The basics of recovery are straightforward. Your main focus should be on staying hydrated and giving your digestive system time to recover. 

Here's what helps most:

• Take small sips of water, oral rehydration solutions, or clear broth

• Once vomiting stops for a few hours, try bland foods

• Toast, crackers, rice or bananas work well

• Add other foods gradually as your stomach settles

Hospital treatment

More serious cases sometimes need extra support. 

You might need hospital care for:

• IV fluids when you can't drink enough

• Severe dehydration needing close monitoring

• Serious infections needing intensive treatment

Most hospital stays are short. You'll be able to return home once you're stable and keeping fluids down.

Food poisoning feels miserable while you're experiencing it, but most people make a full recovery within a few days. Your body is remarkably resilient and knows how to heal itself with the right support.

If you're uncertain about your symptoms, experiencing warning signs, or would simply like reassurance, reaching out for guidance is always the right choice when you're concerned about your health and have appropriate support for your individual situation.

FAQ

How do I know if I have food poisoning or a stomach virus?

The timing gives you clues. Food poisoning often starts within hours of eating something contaminated, while stomach viruses develop more gradually. If others who ate the same food are ill too, food poisoning is more likely. Both conditions cause similar symptoms and need the same basic care regardless.

How long does food poisoning last?

Most cases improve within 1 to 3 days. Some infections last up to a week. The duration depends on what caused your illness and how healthy you were beforehand.

What's the best thing to drink when you have food poisoning?

Oral rehydration solutions work best because they replace lost salts and minerals. You can buy them from pharmacies or make your own. Water alone doesn't replace electrolytes, but it's better than nothing. Sip small amounts frequently rather than drinking large quantities at once.

When should I go to the emergency room for food poisoning?

Can I take Imodium (loperamide) for food poisoning diarrhoea?

Not usually. Anti-diarrhoea medicines can trap harmful germs in your system and make things worse. Avoid them if you have bloody diarrhoea, a high fever, or severe stomach cramps. Your body needs to clear out the contamination. Speak with your pharmacist or doctor before taking any anti-diarrhoea medication.

Should I eat when I have food poisoning?

Wait until vomiting stops before trying food. Start with small amounts of bland foods like toast, crackers, or rice. Add other foods gradually as your stomach settles. Avoid fatty, spicy, or rich foods until you're fully recovered.

How do I know if I'm dehydrated from food poisoning?

Check your urine colour. Dark yellow or brown urine signals dehydration. Other signs include extreme thirst, dizziness when standing, dry mouth, reduced urination, and confusion. Severe dehydration may need medical treatment with IV fluids.

The information is intended for general guidance only and should not be considered medical advice. For personalised recommendations and advice based on your unique situation, please consult a specialist at Thomson Medical. Request an appointment with Thomson Medical today.