Skin
The four types of diaper rash, and how to tell them apart
Start with these five things
Before working through the types, look at the rash itself and answer these. Two of them do most of the work.
- Where is it? Only on the surfaces the diaper touches, or also in the folds?
- Are the creases involved? This is the single most useful question. Irritation spares the creases, because the diaper does not reach into them. Yeast likes them.
- What is the edge like? A soft, blurred edge that fades into normal skin, or a sharp edge that looks drawn on.
- Are there separate spots? Small red dots sitting on their own, just outside the main patch, are a specific clue.
- Is the surface intact? Flat and red, or raised, blistered, weeping, or crusted.
One note before the descriptions: redness looks different on different skin tones. On deeper skin a rash may look darker brown, purple or gray rather than red, and the change in texture, warmth and your baby's reaction to being touched matters more than the color. If the skin feels different and your baby does not like it being cleaned, treat it as a rash even if it does not look red.
1. Irritant dermatitis
The ordinary kind, and the great majority of rashes.
What it looks like: pink to red, shiny or slightly glazed, on the convex surfaces the diaper presses against: the buttocks, the tops of the thighs, the genitals, the lower belly. The edge is soft and blurred. The deep skin creases are usually clear, which is the tell.
What causes it: skin sitting against moisture, and the enzymes in stool breaking down the skin barrier once it is damp. Friction makes it worse.
What it needs: the standard routine. Change as soon as the diaper is wet or soiled, clean gently with water or a fragrance-free and alcohol-free wipe, air the skin, and apply a thick zinc oxide or petrolatum barrier at every change.
How fast it should respond: visibly better within two to three days. If it is not, look at the next three types.
2. A yeast (candida) rash
The most common reason a rash does not clear.
What it looks like: deeper, beefier red than irritation, often with a slightly raised edge that is sharper than a blurred irritant edge. It gets into the creases rather than sparing them. The classic sign is satellite lesions: small separate red spots or tiny pustules sitting on clear skin just outside the main patch, as though they have jumped the border.
What causes it: candida is a yeast that lives on skin normally and overgrows when the area stays warm and damp, when the skin barrier is already broken by an irritant rash, or after a course of antibiotics has cleared the bacteria that usually keep it in check. It is not a hygiene failure.
What it needs: an antifungal. A barrier cream alone will not clear it, and more of the same cream is the most common thing parents do for a week before getting it looked at. Speak to your doctor or pharmacist. Keep the barrier cream going as well, over the top of whatever they recommend, because the skin still needs protecting while it heals.
The pattern to recognize: a rash that improved a little, then stalled, then got redder in the folds, roughly a week in. That sequence is almost always this.
3. A bacterial infection
Less common, and the one to act on quickly.
What it looks like: bright red, often with yellow or honey-colored crusting, small pus-filled spots, blisters, or areas that look wet and weepy. Impetigo, usually caused by staph or strep, is the usual version. A very bright, sharply bordered red around the anus can be perianal strep.
What causes it: bacteria entering skin whose barrier is already broken, which is why it often follows a rash that has been there for a while.
What it needs: a doctor, not a cream from the shelf. It is usually treated with a topical or oral antibiotic. Do not wait the two to three days you would wait on an ordinary rash.
See someone urgently if there is a fever alongside it, if the redness is spreading outwards, if your baby is unusually sleepy or hard to rouse, or if they are feeding much less than normal.
4. An allergic or contact reaction
Uncommon, and the easiest one to identify, because of its shape.
What it looks like: a rash with an edge that looks drawn on, matching the outline of something that touches the skin. A band exactly where a leg elastic sits. A rectangle where a wipe was used. A stripe at the waistband. A patch matching the front panel of the diaper but not the back.
What causes it: a sensitivity to something in contact with the skin. Fragrance and preservatives in wipes are the most common culprits, followed by lotions, creams, laundry detergent on cloth, and occasionally a dye, elastic or adhesive in the diaper itself. True allergy to diaper materials is rare, but it happens.
What it needs: finding and removing the cause. Change one thing at a time and give it three to four days: switch to plain water and a soft cloth for cleaning first, since wipes are the most common cause. If that clears it, reintroduce a simple fragrance-free wipe. If not, change the diaper brand next, then the cream, then the detergent. Changing everything at once tells you nothing.
Photograph it before you change anything. The shape is the evidence, and it fades. It is also what a doctor, or the manufacturer, needs to see.
The other things it might be
Not every rash in the diaper area is a diaper rash. These are worth knowing about so you can raise them:
- Intertrigo: raw, red, sometimes weepy skin only in the deep folds, from skin rubbing on skin in a warm damp crease. Common in chubbier babies and in hot weather.
- Seborrheic dermatitis: greasy yellowish scale, usually in the folds, often with cradle cap on the scalp at the same time.
- Heat rash: tiny clear or red pinprick bumps that appear quickly in hot weather or under too many layers, and settle as quickly once the skin cools.
- Eczema: dry, itchy, scaly patches. It usually turns up elsewhere on the body too, and the diaper area is often one of the last places affected because it stays humid.
- Psoriasis and rarer conditions: uncommon in babies, but a stubborn, sharply defined rash that will not respond to anything is a reason to be referred rather than to keep trying creams.
A quick comparison
Creases spared, blurred edge, responds in two to three days. Irritant dermatitis.
Creases involved, beefy red, small spots outside the patch, will not clear. Yeast.
Yellow crusting, pus, blisters, fever. Bacterial. See a doctor.
An edge shaped like an elastic, a wipe or a waistband. Contact reaction.
If you are not sure
Being unsure is normal, and the four types overlap. A rash that starts as irritation and then gets infected is not one thing or the other; it is both, in sequence.
The practical rule: treat any new rash as the ordinary kind for two to three days. If it is improving, keep going. If it has stalled or got worse, or if it has any of the bacterial signs at any point, have it looked at rather than trying a fourth cream. The routine itself is set out in our full guide to diaper rash. Our guide to when to see a doctor sets out exactly which signs are worth a same-day call.
Common questions
What does a yeast diaper rash look like?
Deeper red than an ordinary rash, involving the skin creases rather than sparing them, often with a slightly raised border and small separate red spots on clear skin just outside the main patch. It typically follows antibiotics or a rash that has been present for several days.
How do I know if a diaper rash is infected?
Pus, yellow or honey-colored crusting, blisters, open weeping sores, or a fever. Any of those means a doctor rather than another day of cream.
Why won't my baby's diaper rash go away?
The most common reason is that it is a yeast rash being treated as an irritant one, and a barrier cream will not clear it. The next most common is that the cause is still there: a wipe, a cream, a food, or simply not enough changes.
Can a diaper rash be an allergy?
It can, though it is uncommon. The clue is shape: a contact reaction has a sharp edge that matches whatever is touching the skin. Change one thing at a time to find it.
Is diaper rash contagious?
Irritant rashes are not. A bacterial infection such as impetigo can be spread by contact, so wash your hands after changes and keep towels and washcloths separate until it has been treated.
What if the rash looks purple or gray rather than red?
On deeper skin tones, inflammation often shows as darker brown, purple or gray rather than red. Judge by texture, warmth, and whether your baby minds the area being touched, not by color.