Itchy rash in infants includes:

• Cradle cap
• Diaper rash
• Stapylococcal scalded skin syndrome (SSSS)
• Impetigo

Common itchy rashes in children:

• Chickenpox
• Measles
• Rubella (German measles)
• Roseola infantum (Herpes virus 6)
• Fifth disease (Parvovirus B19)
• Hand, foot, and mouth disease (Coxackie virus)

Itchy red bumps may be:

• Insect bite
• Acne - whiteheads and blackheads
• Folliculitis -staph infection, looks like acne but without blackheads
• Razor bumps (ingrown hair) appear several hours after shaving
• Miliaria (prickly heat)
• Bumpy hives (allergy to physical stimuli like heat, or stress)
• Side effect of medications

Itchy red non-scaly patches may be due to:

• Mild sunburn
• Hot flashes  in menopause, scombroid fish poisoning, food allergy)
• Hives (urticaria) - mostly in allergies
• Cellulitis  - under-skin staph or strep infection
• Granuloma annulare

Itchy scaly patches may appear in:

• Cold sore
• Severe sunburn
• Fungal infection (athlete's foot, jock itch, scalp ringworm)
• Diaper rash
• Contact dermatitis (eczema)
• Chronic actinic (solar) dermatitis
• Photosensitivity
• Psoriasis
• Discoid eczema
• Lichen sclerosus
• Skin cancer
• Staphylococcal scalded skin syndrome (SSSS) in small children (rare)

Itchy crusts appear after original rash breaks and oozes fluid. It is common in:

• Chickenpox(varicella zoster)
• Shingles(reactivation of varicella zoster)
• Impetigo
• Erythema multiforme

Boils:

• Furuncle, or carbuncle, usually from Staphylococcus aureus infection

Nodules:

• Nodular prurigo
• Erythema nodosum

 Few millimeters or centimeters long snaky burrows may appear in:

• Scabies
• Larva migrans (Creeping eruption, sandworm)

Rash on hairy areas include:

• Dandruff
• Seborrheic dermatitis
• Head lice and pubic lice cause red bumps
• Tinea capitis (scalp ringworm) is fungal infection of the scalp
• Barber’s itch (ringworm of the beard)
• Tinea cruris (jock itch) is fungal infection of the inner thighs and groin
• Genital warts in sexualy transmitted diseases (STDs)
• In hydradenitis suppurativa itchy lumps appear in armpits or in groin.