infection overview for patients

Overview

An infection happens when tiny germs (like bacteria, viruses, fungi, or parasites) enter your body and multiply. This can make you feel unwell. Many infections are mild and get better on their own, but some need medical care.

Infections are very common. Most people have a few infections every year, such as colds or flu. Some infections are more serious and require hospital care.

Infections can affect anyone, of any age. They are more likely to cause serious illness in babies, older adults, pregnant people, and people with weakened immune systems.

Symptoms

Common symptoms

• Fever or chills
• Cough, sore throat, or runny nose
• Feeling very tired or weak
• Body aches or headache
• Nausea, vomiting, or diarrhea

Symptoms in children

• A high temperature, especially in a baby under three months old
• Becoming unusually drowsy or floppy
• Refusing to feed or drinking less than usual
• A rash that does not fade when pressed
• Crying more than usual or being very irritable

Symptoms in older adults

• Confusion or feeling unusually sleepy
• Falls or poor balance
• Loss of appetite or low energy
• A body temperature that is high or low
• A change in toilet habits, such as needing to urinate more often

Causes

Main causes

• Bacteria — single-celled germs that can cause infections like strep throat or urinary tract infections
• Viruses — tiny germs that need living cells to grow, such as colds, flu, or COVID-19
• Fungi — organisms like yeasts and molds that can cause skin or lung infections
• Parasites — organisms that live on or in a host, such as malaria or intestinal worms

Risk factors

• Being very young or very old
• Having a long-term health condition such as diabetes or lung disease
• Taking medicines that weaken the immune system
• Living or working in crowded places
• Travel to areas where certain infections are common
• Not being up to date with recommended vaccines

When to see a doctor

See a doctor urgently if:

• If you have a fever and feel very unwell
• If you have difficulty breathing or chest pain
• If you are confused or not your usual self
• If you have a severe headache, stiff neck, and a rash
• If you cannot keep fluids down and have signs of dehydration

Book a routine appointment if:

• If an illness lasts longer than a week
• If you have a cough, cold, or flu-like symptoms that are not improving
• If you have a skin sore that is red, warm, or painful
• If you have questions about your symptoms or whether you need treatment

Diagnosis

A healthcare professional will ask about your symptoms, medical history, and any recent travel or contact with sick people. They will also examine you.

Tests that may be done

• Blood tests — checking for signs of infection, such as a high white blood cell count or inflammation
• Urine tests — checking for infection in the bladder or kidneys
• Throat or nose swabs — checking for viruses or bacteria
• Imaging scans, such as a chest X-ray, if needed
• Stool tests — if you have diarrhea that lasts a long time

What to expect at your appointment

You may be asked to provide a sample (blood, urine, or a swab). Results can take from minutes to a few days. The doctor will use these results, along with your symptoms, to decide the best next steps.

Treatment

Treatment depends on the type of infection and how serious it is. Many viral infections get better on their own. Bacterial infections may need antibiotics. Fungal infections may need antifungal treatment. Always follow the advice of your healthcare professional.

Self-care at home

• Rest as much as you need
• Drink plenty of fluids to stay hydrated
• Use over-the-counter remedies for fever or aches — ask your pharmacist for advice
• Keep warm and comfortable
• Wash your hands often to avoid spreading germs to others

Medical treatments

For bacterial infections, a healthcare professional may prescribe antibiotics. For fungal infections, antifungal medicines may be used. For some viral infections, antiviral medicines can help. Always take the full course exactly as prescribed, and do not share medicines with anyone else. Some serious infections need care in a hospital, which may include oxygen, fluids through a drip, or specialist treatment.

When is surgery considered?

Surgery is rarely needed for most infections. However, some infections, such as an abscess (a collection of pus) or an infected wound, may need a small procedure to drain the pus or clean the area.

Living with this condition

While your body fights an infection, listen to your body. Take time to rest, drink fluids, and avoid heavy activity. If you are on a course of medicine, finish it as prescribed. Keep track of your symptoms and seek help if they worsen.

Lifestyle tips

• Prioritise sleep and rest
• Avoid alcohol and smoking while unwell
• Stay up to date with recommended vaccines and check-ups
• If you are prescribed antibiotics, do not share them with others

Diet and exercise

Eat small, nutritious meals if you feel like eating, and drink water regularly. You do not need to force yourself to eat. Gentle activity like walking is fine if you feel well enough, but heavy exercise can wait until you recover.

Mental health and emotional wellbeing

Being ill can affect your mood and make you feel anxious or low. This is normal. Talk to friends or family about how you feel, and be kind to yourself. If your mood stays very low or you are struggling to cope, speak to your healthcare professional. If you are having thoughts of harming yourself or are in crisis, call your local emergency number or a crisis helpline immediately.

Prevention

Many infections can be prevented with simple steps like handwashing, safe food handling, covering your mouth when you cough, staying home when you are unwell, and staying up to date with recommended vaccines.

Vaccines

Vaccines are one of the best ways to prevent many infections. They teach your immune system to fight germs before they make you sick. Talk to your healthcare professional about which vaccines are recommended for you.

Screening programmes

For some infections, regular screening is recommended, for example during pregnancy or for people with certain health conditions. Ask your healthcare professional what screenings apply to you.

Complications

If left untreated

• An infection can become more severe and spread to deeper tissues or organs
• Sepsis — a life-threatening condition where the body’s response to infection harms its own tissues and organs
• Long-lasting symptoms or a chronic infection
• Dehydration or kidney damage from a severe digestive infection

Long-term outlook

Most people who get an infection recover fully with rest and simple care, or with the right treatment. Even for more serious infections, prompt medical care can make a big difference. Your healthcare team is there to help you through it.

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