By day two a wound should hurt less than it did. Hurting more is the earliest reliable sign.
1Draw round the edge of any redness with a pen and write the time beside it.
2Redraw and re-time every few hours. Past the line is progression, inside it is genuine improvement.
3Measure swelling the same way: a piece of string round the limb, marked and dated.
4Watch the direction of travel, not the appearance on any one day.
5Red streaks running toward the armpit or groin: that is lymphangitis, get help urgently.
6A tense, exquisitely tender lump is an abscess. Antibiotics alone often will not clear it, it needs to drain.
7Fever, rigors, confusion or feeling profoundly unwell: read the sepsis page and ring 999.
Day 2
Pain should be improving
The technique
Pen line, with the time on it
Red streaks
Urgent, spreads fast
Wakes them at night
Act before other signs
The mistake that costs lives: Dismissing pain that is getting worse because the wound looks unremarkable. Increasing pain after the first 24 to 48 hours comes before the redness, the discharge and the fever, and it is the sign most often talked away. Throbbing rather than sore, or waking them at night, is enough on its own.
Increasing pain after the first day is the earliest reliable sign. Red streaks tracking away from the wound mean it is spreading through the lymphatics, and that is the point at which time stops being on your side.
Every wound in this app leads here if it goes wrong, and in a household without easy antibiotics this is the page that decides outcomes. It is about noticing, in the right order, over days.
Read clean and dress a wound first. Nothing on this page substitutes for irrigating properly on day one.
The timeline that tells you
Normal healing and early infection look similar on day one. They diverge on day two, and the direction of travel is the signal.
Mark the edge
The single most useful practical technique on this page, and it costs nothing.
Draw around the edge of any redness with a pen, and write the time next to it.
Nobody can reliably judge from memory whether redness has spread since yesterday. The eye adjusts, the impression drifts, and two people will disagree. A line on the skin converts an argument into a measurement.
Redraw and re-time every few hours where you are worried.
Spreading past the line is progression, and that changes the plan.
Retreating inside the line is improvement, and is genuinely reassuring.
Do the same for swelling by measuring the limb circumference with a piece of string, marked and dated.
The stages, and where each one leads
Local infection. Redness, heat, swelling and pain confined to the wound and its immediate edge. Some discharge. The person is otherwise well. Manage at home, watch closely.
Cellulitis. Infection spreading into the surrounding skin and soft tissue. Redness extends well beyond the wound, the area is hot, tight, shiny and tender, and the person may start to feel unwell. This needs antibiotics.
Lymphangitis. Red streaks running away from the wound toward the nearest lymph nodes: up the arm toward the armpit, up the leg toward the groin. The nodes themselves may be swollen and tender. This is spreading through the lymphatic system and it moves fast.
Abscess. A collected pocket of pus, felt as a tense, exquisitely tender, sometimes fluctuant lump. Antibiotics alone frequently will not clear it, because they do not penetrate a sealed collection well. It needs to drain.
Systemic infection and sepsis. Fever, rigors, confusion, fast breathing, feeling profoundly unwell. This is the emergency the whole page exists to prevent.
Red streaks
What you can actually do
Ranked by how much difference each makes.
Irrigate properly on day one. Nothing else on this list comes close. See wound care.
Rest and elevate the affected part above the heart. Reduces swelling, improves drainage, and is genuinely effective.
Keep it clean and change the dressing daily, more often if it soaks through.
Let it drain. A wound producing discharge with somewhere to go is far safer than one sealed over. Do not close an infected wound, and if you have closed it, open it. See closing a wound.
Warm compresses, several times a day, which increase local blood flow.
Remove anything foreign. A retained splinter, thread or piece of grit will keep the infection going indefinitely whatever else you do.
Pain relief and fluids.
Salt water soaks for a hand or foot, several times a day. Cheap and mildly helpful.
Nutrition. Healing is metabolically expensive and protein matters. This is one of the arguments for the calorie planning in the food chapter.
What does not help, despite being reached for: antiseptic poured into the wound, which damages healing tissue; sealing it under an occlusive dressing; and squeezing an undrained swelling, which forces infection deeper into the tissues.