Half an inch. That was the measurement in the message, and it is the reason I am writing this rather than sending back a 2 line reply, because most people who write to me about spots on their legs say “big” or “nasty” and leave me guessing, and this woman said a tense clear blister like a burn, then it bursts, then a raw round sore, then the skin around the edge peels off until the thing is half an inch across. Burns, itches, hurts. Started as 1, now 4, working their way down the leg. Loose clothes, daily shower, exercise, eats well. Fibromyalgia. Recurrent MRSA after a hospital stay when she was 12 or so. No primary care doctor and cannot work out how to get one, though she does see an OB/GYN.
The Blister, The Burst, And The Peeling Rim
That sequence is the important bit, and I would rather over explain it than skip past it.
What Ordinary Blisters Do
Friction blisters, burn blisters, and most bites form a blister, and then the blister dries and the roof flattens back down. They do not keep eating outwards.
What Hers Are Doing
A blister that breaks and then becomes an erosion, a shallow raw disc, with a ring of loose dead skin around it that lifts away in flakes over several days. Dermatologists call that ring a collarette. It happens when something has split the skin just below its top layer across a circle, so the top layer comes off in one piece and the edge unravels afterwards.
Very few things do that. The one that does it most, by a long way, is a staph infection. Some strains of Staphylococcus aureus make a toxin that cuts the skin’s upper layer loose from the layer under it. The gap fills with fluid, that is the blister; it ruptures easily, that is the burst; the loose roof and rim slough away, that is the half inch. Doctors call it bullous impetigo, and in an adult it is very often a staph that carries the MRSA resistance, because those strains are the ones that hang around on people for years.
And she has told us, almost in passing, that she has had recurrent MRSA since childhood. I read that line 3 times. It is the single most useful fact in the whole message, and she put it near the end, after the bit about eating healthy, as if it were less relevant than her diet. It is not. MRSA does not leave. It sits in the nose and on the skin care and comes back after a stressful month, a course of antibiotics for something else, or a week of bad sleep, and it comes back as exactly this: blisters on the legs and arms that break down into round sores and travel by scratching.
I would put money on it. I would not put her health on it, which is a different thing, and that is what the next 2 sections are about.
What Else It Could Be
I am not a dermatologist, and I do not want anyone reading this to decide from 5 photos that they know.
- Bites, from bed bugs, fleas, or a spider, can blister hard in some people and then break down, and the tell there is new spots every few mornings and a bed, a sofa, or a dog in common.
- A plant or a chemical on the skin can do it, but usually in a streak or a patch where the contact was, not scattered dots down a leg.
- There is a short list of uncommon, serious blistering conditions that I am not going to name one by one, because naming them causes more panic than good, and every one of them gets found the same way, which is by a person in a clinic looking at the skin and taking a swab.
The Swab Is The Whole Answer
Here is the entire diagnostic test. A cotton bud, wiped across the wet base of a fresh sore or a just burst blister, into a tube, off to a lab. 2 or 3 days later a result comes back that says whether staph is there, whether it is MRSA, and which 3 or 4 antibiotics will actually kill it, because the usual ones will not. That piece of paper decides the treatment, and nothing else does. If staph grows, it is a specific oral antibiotic, sometimes a cream as well, and sometimes a nasal ointment for a week to clear the carriage so this stops happening every 18 months. If nothing grows, the search moves to bites or a skin condition, and that is a different conversation.
One thing to know. Do not start any leftover antibiotic before the swab. A single dose can make the culture come back clean while the infection carries on underneath, and then everybody is confused for another fortnight.
Getting Seen This Week Without A Family Doctor
This bit made me cross, not with her, with the system. “I can’t figure out how to get a primary care doctor” is something I hear every week, and it is a real problem, but it is not this week’s problem. This week she needs a swab and a prescription, and she does not need a primary care doctor to get either.
The Fast Doors
- Urgent care will do it the same day, no referral, and with 4 spreading sores and an MRSA history that is where I would go tomorrow morning.
- Her OB/GYN will also do it, and I think people do not realise this. Any physician can swab a wound and write for an antibiotic, and an office that already knows her will fit her in for “a skin infection that is spreading” faster than any new patient line.
- Telehealth is fine for a look and a script but cannot take a swab, so it is the fallback, not the first call.
The Longer Fix
Every county has at least 1 federally funded community health centre that takes people with any insurance or none on a sliding fee, and the government’s health centre finder lists them by zip code, and that is the realistic route to a doctor who will still be there next year. If she is on Medicaid, the number on the back of the card assigns a primary care provider over the phone in about 10 minutes, which almost nobody knows.
What To Do Tonight
- Leave the blisters alone. Do not pop them, and do not pull the peeling skin. The roof of a blister is the best dressing it will ever have.
- Wash each sore once a day with plain soap and water, pat dry with a paper towel, and cover it with a non stick dressing. Covered sores spread less and heal faster.
- Her own towel, changed daily, bedding washed hot, and no shared razors or blankets. If this is staph, that is how spot 3 became spot 4, and how it becomes somebody else’s spot 1.
- Nails short and hands washed after touching any of them. Scratching in her sleep is my guess for how it is travelling down the leg.
- No pool, no gym mat, no shared shower until they have closed.
When It Stops Being A Clinic Problem
Same day emergency department if any of these turn up:
- Redness spreading out from a sore, or a red streak running up the leg.
- A fever, the chills, or suddenly feeling rough.
- A sore that goes hot and swollen and much more painful, or one that grows past an inch.
- Blisters in the mouth or around the eyes.
- A joint that starts to hurt and swell.
Staph in the skin is a nuisance. Staph in the blood or a joint is an emergency, and the gap between the two is often just a couple of days of waiting to see.
She mentioned the fibromyalgia, and I want to say plainly that fibromyalgia does not do this. It is not the cause, and it should not be in the differential. The reason it matters at all is that people who have lived with chronic pain for years have usually been told a hundred times that a new symptom is stress, or is the condition they already have, and they learn to sit on things. This is not one to sit on. 4 spreading blistering sores in someone with a known MRSA history is a good reason to walk into an urgent care and say those exact words at the desk.
Let me know what the swab says. I really do want to know.
Written for information, not as medical advice or a diagnosis. Blisters that spread, break down, or come with fever need to be examined in person.
