What do I do if I cut myself badly with a tool?

Pressure, elevation and when to stop treating it yourself. What a workshop cut needs beyond a plaster, the tetanus question, the injuries that need A&E regardless of how they look, and the high-pressure injection injury nobody recognises.

Difficulty: beginner
Time: 15 min
Read: 6 min
Safety: warning

Short answer

Firm direct pressure with a clean dressing, held for ten minutes without lifting it to look, with the injury raised above heart level. Then assess: deep, gaping, numb, on a joint or a tendon, still bleeding, dirty, or from a power tool — all of those go to a minor injuries unit or A&E rather than into a plaster.

Most workshop cuts are minor and heal fine. The ones that go wrong do so for predictable reasons: bleeding was not controlled properly, a tendon or nerve injury was not recognised because the wound looked small, dirt was left in, or the person waited to see how it went. The response is the same for all of them — control the bleeding first, then assess honestly.

Safety

Ring 999 for bleeding that will not stop with firm pressure, for a wound that spurts, for any amputation or partial amputation, for a deep wound to the wrist, palm or a joint, and for anyone who becomes pale, cold, clammy or confused. Do not remove an object that is embedded — press around it, not on it. Keep any severed part: wrap it in a clean dry dressing, seal it in a plastic bag and put that bag on ice, never the part directly on ice.

What you'll need

Clean dressings or a clean cloth
Running water
A first aid kit with sterile dressings and tape
Someone else in the house, if possible (optional)

Step by step

Stop and make the tool safe.Switch off, unplug or remove the battery before you do anything else. A running tool left on the bench turns one injury into two, and adrenaline makes people careless in the next thirty seconds.
Apply firm direct pressure.A clean dressing or cloth pressed hard onto the wound. Firm and continuous — pressure works by stopping flow, and lifting it to look restarts the bleeding every time. Ten minutes without checking.
Raise the injury above the heart.Hand or arm above shoulder height, leg raised while lying down. It reduces the pressure at the wound and it costs nothing.
Add dressings on top rather than replacing them.If blood comes through, put another dressing over the first and keep pressing. Removing a soaked dressing removes the clot that was forming.
Do not remove anything embedded.A blade fragment, a nail, a splinter of metal or a piece of the workpiece. Press around it with padding either side, not on it, and get it looked at. Removing it can start heavier bleeding and can cause more damage on the way out.
Ring 999 for the serious signs.Bleeding that does not slow after ten minutes of firm pressure, blood that spurts or pulses, an amputation or partial amputation, a deep wound to the wrist or palm, or anyone becoming pale, cold, clammy, faint or confused. Do not drive yourself.
Clean a minor wound properly once the bleeding has stopped.Rinse under clean running water to flush out dust, sawdust, metal or grit. Do not scrub, and do not use antiseptic straight into an open wound. Dry the surrounding skin and cover with a sterile dressing.
Test for tendon and nerve damage before deciding it is minor.Can you move the finger or the joint through its full range against resistance, and is the sensation normal on both sides of the digit? A tendon or nerve injury can present as a small clean cut with no bleeding and full appearance of being fine. Any loss of movement or feeling means it needs assessing today.
Take the deep and dirty ones to be seen.Gaping wounds that will not stay closed, anything longer than about a centimetre and deep, anything over a joint, anything from a power tool, and anything contaminated with soil, rust or preservative. Wounds that need closing are best closed within a few hours.
Check your tetanus status.Any wound contaminated with soil, dust, manure or rust, and any deep or puncture wound, raises the question. Most UK adults have had a full childhood course, but if you are unsure or it has been a long time, ring NHS 111 or your GP and ask.
Watch for infection over the following days.Increasing pain after the first day, spreading redness, swelling, heat, pus, a red line tracking up the limb, or a fever. Any of those needs medical advice rather than waiting.

Tips

Keep a real first aid kit in the workshop, not just plasters — sterile dressings, a bandage, tape, gloves and eyewash. A cut is not the moment to discover the kit is in the house.
Blue plasters are used in food environments because they show up if they come off. In a workshop, any waterproof fabric plaster is better than a fabric one because it survives dust and washing.
A high-pressure injection injury — from a grease gun, an airless paint sprayer or a hydraulic line — looks like a pinprick and is a surgical emergency. The material spreads inside the tissue and causes severe damage within hours. Go straight to A&E and say what was injected.
Tell someone you are working alone with power tools, and keep a phone in your pocket rather than on the bench. Reaching a phone across a workshop while bleeding is harder than it sounds.

If it doesn't work

Bleeding will not stop after ten minutes of firm pressure

Cause: The wound is deeper than it appears or has damaged a vessel — Fix: Keep the pressure on, keep it raised, add dressings on top, and ring 999. Do not keep lifting to check.

A small clean cut, but the fingertip is numb on one side

Cause: A digital nerve has been divided even though the wound looks trivial — Fix: Go to be assessed today. Nerve and tendon repairs have much better outcomes when done early, and the wound size tells you nothing about the depth.

The finger will not bend or straighten properly

Cause: A tendon has been cut or partially cut — Fix: A&E or a minor injuries unit the same day. A partially cut tendon can rupture completely later if it is not identified.

A tiny puncture from a grease gun or a paint sprayer, barely bleeding

Cause: High-pressure injection injury — material has been forced into the tissues — Fix: Go straight to A&E and tell them what was injected. This is a surgical emergency despite looking like nothing, and delay makes the outcome much worse.

Redness spreading and increasing pain after two days

Cause: Wound infection — Fix: Contact NHS 111 or your GP the same day. A red line tracking up the limb, fever or feeling unwell means it needs urgent attention.

Questions people ask

When does a cut need stitches?

Broadly: when the edges will not stay together on their own, when it is deep enough to see fat or deeper tissue, when it is over a joint or on the face, or when it keeps bleeding. Closure is best done within a few hours, so it is better to be seen and told it is not needed than to wait.

Do I need a tetanus jab?

It depends on your vaccination history and on the wound. Deep, dirty and puncture wounds, and anything contaminated with soil, are the ones that raise it. If you are unsure whether you have had a full course and boosters, ring NHS 111 or your GP — they will check your record.

Can I use superglue on a cut?

Medical tissue adhesives exist and are used clinically, but household superglue is a different formulation, is not sterile, and can trap contamination in the wound. Use adhesive strips for a clean shallow cut that is holding together, and get anything more seen.