Cellulitis
Reviewed by Andrew Schox, BSc(Hons) PGradDipPod MPod, October 2026
Cellulitis is a bacterial infection of the skin and the tissue just under it. It is common, and in more than 80 per cent of cases it affects the legs or feet. The main sign is an area of skin that is red, warm, swollen and painful, and it may blister. It often needs antibiotics from a doctor, so a new red, painful patch needs to be seen the same day. With the right care, you should start to improve within 2 to 3 days. It can come back, so looking after your skin and any leg swelling matters.
What is it?
Cellulitis is an infection caused by bacteria. It affects the deeper layers of your skin (the dermis) and the tissue just under them. It makes the skin painful, warm, swollen and red, and blisters can form.
It can happen anywhere on the body, but the lower leg is the most common place. In more than 80 per cent of cases it is in the legs or feet.
Who does it affect?
Anyone can get cellulitis, but some things make it more likely. These include:
- swelling in the leg caused by fluid build-up, including lymphoedema (swelling that happens when the lymph system, which drains fluid from your tissues, isn't working well)
- obesity
- athlete's foot (tinea) and soggy, cracked skin between the toes
- cracks in the skin of the soles of your feet
- leg ulcers, eczema and past injuries to the leg
- weak leg veins (venous insufficiency) or past vein surgery
- poorly controlled diabetes and liver disease
- injecting drugs
A history of cancer raises the chance of having cellulitis again and again. If you have had cellulitis before, you are more likely to get it again.
Signs and symptoms
The skin is usually painful, hot and swollen, and it looks red. The redness can be harder to see on brown or black skin. The area often feels tight, and the skin can look glossy and stretched. It is usually on one side only, such as one leg or one foot.
The redness may spread, and the nearest glands may swell. It may start after a graze, a bite, another small injury or athlete's foot. You may also feel flu-like.
In more severe cases there can be a high temperature (fever), shaking chills, nausea and vomiting, dizziness and confusion. These are signs the infection has spread deeper.
What causes it?
The bacteria that cause cellulitis often live harmlessly on your skin. Trouble starts when they get into a break in the skin, such as a cut, graze, bruise, animal or insect bite, leg ulcer, or dry cracked skin from eczema or athlete's foot. Even a scratch can be enough.
Sometimes no break in the skin can be found, and in most cases the exact trigger is never known. The most common bacteria involved are streptococci and Staphylococcus aureus (often called "staph").
How is it diagnosed?
Cellulitis is diagnosed from how the skin looks and feels. Your practitioner will look at the size and edges of the redness, and check for warmth, swelling, tenderness and blisters. They will ask whether you have a fever or feel unwell, and look for a skin break or athlete's foot that may have let the infection in.
They may mark the edge of the redness with a pen and note the date and time. At each check, they can see whether the redness has spread past the line.
Some other skin problems can look like cellulitis. If it isn't clear what is going on, a doctor or skin specialist (dermatologist) may be asked to review it. Getting the diagnosis right matters, because antibiotics that aren't needed add to antibiotic resistance.
Treatment
Cellulitis often needs antibiotics. Your doctor decides which one, how much and for how long, following current guidelines.
Looking after it at home
Take your antibiotics exactly as directed. If a pen line has been drawn around the redness, keep an eye on it and check whether the redness goes past it.
Treatment from your podiatrist
Your podiatrist can check your feet for skin breaks, cracks, soggy skin between the toes and athlete's foot. They can mark and date the edge of the redness so any spread is easy to see. They will make sure you see a doctor the same day if the infection looks new or is getting worse.
After the infection has settled, your podiatrist can keep treating athlete's foot, cracked skin and wounds that may have let it in.
Other options
If you haven't started to improve within 2 to 3 days, or the redness or swelling is spreading, you need a medical review. The doctor may swab the area to test for bacteria, but only in certain cases. These are when the skin is broken and there was a deep injury or contact with water that may carry germs, or when antibiotics haven't worked.
You may be sent to hospital if you can't take antibiotics by mouth, if the infection keeps spreading despite tablets, if you have a weak immune system, or if you are finding it hard to keep up with treatment.
Recovery
With the right treatment you should start to improve within 2 to 3 days.
Cellulitis can come back. Estimates for another episode after a leg infection range from 8 to 20 per cent, and up to 29 per cent in some groups. It is more likely if you have lymphoedema, swelling in your lower legs, a history of cancer or obesity. Each episode is thought to damage the lymph vessels, which makes the next one more likely.
Preventing it
If you have lymphoedema, managing it is the best-supported way to lower the chance of cellulitis coming back. Compression, such as compression garments, has consistently helped. Ask your doctor or practitioner when and how to use it.
Check your feet often, including between your toes and on your soles, for cracks, soggy skin, athlete's foot and wounds. Keep treating these problems and have wounds looked after. It isn't yet clear whether treating athlete's foot and leg ulcers lowers the chance of cellulitis returning, but doing so is still recommended.
If you keep getting cellulitis, talk to your doctor or a specialist about your options.
When to see a podiatrist
When to book
Book an appointment with your podiatrist if you have swelling in your legs or feet, athlete's foot, cracked or soggy skin between your toes or on your soles, or a wound or ulcer that isn't healing. Also book if you have had cellulitis before and want to lower the chance of it coming back.
When to get help sooner
A new patch of skin on your foot or leg that is red, warm, swollen and painful needs urgent medical assessment the same day. See your GP today, or go to an urgent care clinic or the nearest emergency department. Don't wait to see whether it settles.
Call your local emergency number if the redness is spreading very quickly and the pain is severe. Call it too if you suddenly feel very unwell with a fever, a fast heartbeat, cold or sweaty skin, dizziness or confusion, or purple patches on your skin. If you have cellulitis and you also feel very unwell, with confusion or slurred speech, severe shivering or muscle pain, severe breathlessness, mottled or discoloured skin, or little or no urine, this could be sepsis: call your local emergency number.
These also need urgent medical assessment: go to the nearest emergency department, or see your GP today.
- Redness on your face or around your eye.
- Skin that goes dusky or purple, or blisters over the red area.
- Severe pain that seems out of proportion to how the skin looks.
- A fever, vomiting or unexplained diarrhoea.
- A flat red rash over a large area of your body, or red eyes.
- Red streaks spreading from the area, a fever that won't go away, or unusual drowsiness.
- Redness or swelling that is spreading while you are being treated.
Get urgent medical assessment too if you think you have cellulitis and you have diabetes, a weak immune system, severe lymphoedema, a human or animal bite, or you smoke. The same applies to a baby under one year, a young child, or an older or frail person.
Frequently asked questions
Can athlete's foot cause cellulitis?
It can play a part. Athlete's foot (tinea) can leave the skin dry, cracked or soggy, especially between the toes. Bacteria can get in through these breaks. Having a fungal infection of the foot is strongly linked with cellulitis, so it is worth treating.
How is cellulitis different from erysipelas?
Erysipelas is a more shallow form of the infection, usually caused by streptococcal bacteria. It tends to have sharply edged borders and comes on faster. It is hard to tell apart from cellulitis, and because the bacteria are the same type, it is treated the same way.
What does cellulitis look like on darker skin?
The skin is still painful, hot and swollen, but the redness may be less obvious on brown or black skin. Go by the other signs too: warmth, swelling, tenderness, tight shiny skin and blisters. If you are unsure, have it checked the same day.