Last updated on May 8, 2021.
It is hard to miss the characteristic and ring-resembling red scaly raised patches of ringworm. If you think ringworm has anything to do with worms, it’s time to learn more about it. Here is everything you need to know about ringworm, reviewed by paediatrician Dr. Eddie Cheung.
What is ringworm?
Ringworm (dermatophytosis or tinea corporis) is not a worm. It is a mild common skin infection in both humans and animals, caused by fungi such as trichophyton. It causes circle-shaped scaly rashes with raised edges that look like a worm. The rash is usually itchy.
The fungi thrive in warm humid environments, such as summers in Hong Kong. If you sweat heavily or have a weakened immunity such as from diabetes, etc., the risks of getting ringworm increases.
Different types of ringworm are found in various body parts: hands (tinea manuum), body (tinea corporis), nails (tinea unguium/onychomycosis) and beard (tinea barbae). Athlete’s foot (tinea pedis) is a foot infection, affecting more men than women. Jock itch (tinea cruris) infects the groin, inner thighs or buttocks. Infection of the scalp (tinea cruris) is mainly seen in children between 2 and 10.
A doctor makes a diagnosis by examining the skin areas affected. Sometimes, they may take a small sample of the skin for microscopic examination or a test.
Ringworm is contagious. That being said, most of them will go away in 2 weeks time with topical anti-fungal treatment. Your child can return to school or nursery after being treated.
Incubation period: Usually 1-3 weeks.
Infectious period: While lesions are visible.
How is ringworm transmitted?
Ringworm is spread via close contacts with someone who has it, contaminated objects such as hats and towels, or contact with an infected animal for instance dogs, cats and farm animals, and contaminated soil.
You can also contract the fungi in warm damp environments like public showers and pool areas.
Signs and symptoms of ringworm
General signs and symptoms
- Intensely red, itchy or dry rash.
- Ring-shaped rash with a raised scaly border and a clear centre.
- Patches gradually increase in size and appear on more areas of the body.
- Flaking or peeling skin.
Symptoms according to body locations:
Scalp: Red bald spots covered in thick crust that causes intense itch. Sometimes pus can appear from sores. Hair loss in areas affected. Swollen lymph nodes.
Beard: Red scaly bumps that itch on the face and upper neck . Fluid-filled bumps that look like acne. Hair loss in areas affected.
Groin (jock itch): Red, swollen, itchy rashes in the skin folds of where the legs meets the body. The rash then spreads to thighs, waist and buttocks.
Feet (athlete’s foot): Skin between the toes, on the bottom and/or sides of the feet become dry, scaly and itchy. The skin infected may peel. Blisters and unpleasant odour can occur.
Hands: Deep cracks on the palms. Dry skin.
Nails: One or more nails can be infected, especially toenails. Thickening, whitish or yellowish discolouration, crumbling of nails.
When should you see a doctor?
Visit your doctor if
– you suspect ringworm;
– symptoms do not improve or worsen after treatment for 2 weeks;
– ringworm has affected the scalp. Anti-fungal treatment require a prescription from your doctor;
– your immunity is weak, e.g. due to long-term use of corticosteroids, e.g. hydrocortisone.
How is ringworm treated?
Treatments vary with severity and body parts involved. Medications put on skin are for mild infections, while those taken by mouth are for more serious ones.
Scalp and nails: Oral prescription agents, such as griseofulvin, terbinafine and fluconazole are usually prescribed. Ringworm should clear in 1-3 months. Anti-fungal shampoo (selenium sulfide) is often required for everyone living together, not only the patient, to prevent is spreading further.
Athlete’s foot: Use terbinafine cream or spray 1-2 times daily for 2-4 weeks. Oral medications are for chronic or extensive cases. Your child may also use anti-fungal powder on feet and shoes.
Jock itch: Anti-fungal cream or spray is applied twice daily for 10-14 days. It is essential to treat an athlete’s foot at the same time if it is present. Otherwise, jock itch can return.
Points to note
– Do not scratch the rash as it can spread to other skin areas.
– Do not stop using the medications sooner than instructed to avoid incomplete fungal clearance and recurred infection. Apply them for an additional week after the rash has disappeared.
– The duration of treatment can be very long and you need to be patient.
– It is important to keep the affected area clean and dry.
– You need to talk to your doctor regarding the pros and cons of anti-fungal medication use.
Here are some tips to prevent ringworm.
- Wash and dry your body thoroughly daily, especially after contact sports and activities that cause sweating or involve touching the soil.
- Avoid sharing personal items with an infected person.
- Change your socks and underwear every day.
- Wash clothing, linens and towels regularly with soap and hot water.
- Dispose of any items that may have fungus on them, e.g. hats, brushes and towels.
- Avoid tight-fitting clothes during infection.
- Do not walk barefoot on damp or communal floors, e.g. the gym and the pool.
- Do not wear shoes that do not allow sufficient air circulation.
If you have a pet at home
- Wash your hands with soap and water after playing with pets.
- Take it to see a veterinarian if symptoms occur, e.g. patches of missing fur.
- Wear gloves and long sleeves when handling pets with ringworm.
- Clean and disinfect areas and objects your pet has been in contact with.
If your child plays sports
- Shower as soon as possible after playing sports.
- Wash your sports gear and uniform regularly.
- Do not share sports gear with other players.
Dr. Eddie Cheung 張蔚賢醫生 is a specialist in paediatrics. He received his paediatric training in Queen Mary Hospital and post-fellow paediatric cardiology training in Grantham Hospital/ Queen Mary Hospital. He is a Fellow of the Hong Kong College of Cardiology, the Vice President of Hong Kong Society of Paediatric Cardiology and Consultant of Hong Kong Association of Cleft Lip and Palate. He is currently working as Director of Paediatric Centre of HK Medical Consultants and serves as Infection Control Officer at the Hong Kong Adventist Hospital.