Oops! Ouch!Now What?

When a kitchen knife slips and you instinctively grip an injured finger, your first thought — after “Eww, I can’t look” — is probably to stop the bleeding and bandage it up, so you can finish prepping dinner. But not every scrape or bump is straightforward. How deep is too deep for a Band-Aid? What if a burn blisters? Is it a sprain or a break? We asked emergency room doctors, some of whom train paramedics for these exact situations, how to safely assess and handle many mishaps on your own — and when to seek medical help.

Read on to learn about cuts, burns, sprains and breaks, head bumps and goose eggs and insect bites, stings and rashes.

We’ve also included an essential list of supplies.

Kitchen knives are high on the list of hazards, as are jaggedly opened canned goods, cheese graters and mandolines that can slice your fingertips. “And yes, avocados are still the bane of everyone’s existence,” said Dr. Lekshmi Kumar, an associate professor of emergency medicine at Emory University School of Medicine and medical director of emergency medical services at Grady Health System in Atlanta. Broken glass, plus sharp table edges that can cause a gash if you crash into them, are also big culprits.

Immediately apply pressure with a clean cloth to stop the bleeding. This can take up to five minutes, depending on how deep the cut is, and it’s crucial not to peek. “That removes the clotting factors and makes it take longer,” said Dr. Tabitha Cheng, an associate medical director at the U.C.L.A. Center for Prehospital Care. Then rinse the cut under running water (tap is fine), make sure there is no debris in the wound and apply petroleum jelly or an antibiotic cream, like Bacitracin, and a sterile bandage.

If the cut has edges that easily come together, you can use a liquid bandage to keep it closed and protected; just make sure to let the glue dry before you place a regular bandage on top of it, Dr. Kumar said. For any cut: Once a scab has formed, remove the bandage and let it air out; it will heal better without moisture getting trapped. Watch for signs of infection, like redness around the cut, warmth of the skin, swelling, increased pain or pus. (If it’s itching, that means it’s healing, Dr. Kumar said. “Itching is normal as the skin stretches to heal.”)

Determining if a cut is serious enough to need stitches is complicated. “Even doctors have to sometimes put a Q-Tip in there to see how deep it is,” Dr. Kumar said. Rules of thumb: Cuts on the face (which can scar more awkwardly without stitches), over joints (which gape and don’t stay shut) or near tendons or arteries need urgent medical attention, as does a cut that clearly goes through multiple layers of skin, gapes or doesn’t stop bleeding in five minutes (especially if you are on blood thinners). Also see a doctor if there is debris, like metal or glass, in the cut, or if it starts to show signs of infection. If the sharp implement was dirty or rusty, bacteria can invade the wound, so a doctor should evaluate it. They may also ask if you are up-to-date on tetanus shots, and give you one if necessary.

All sharp teeth — from dogs, cats or toddlers — carry bacteria and pose an increased risk of infection. Cats, especially, create puncture wounds that are hard to thoroughly clean out, Dr. Cheng said. If a bite breaks the skin but is more like a scrape, you can clean it with warm, soapy water, and treat it at home as you would a cut, checking for signs of infection. Anything deeper or more complicated might require antibiotics. See your primary care physician or head to urgent care.

Small burns from hot pans, curling irons or splattering oil are most common. Considering a home improvement project? Watch out for electrical burns and chemical burns from things like paint thinner.

Call 911 right away for burns that cover a large area of your body — for example, if you spill a pot of boiling pasta water on yourself. “If a burn covers more than 20 percent of an adult’s body or 10 percent of a child’s, even if it’s superficial, it needs immediate attention,” Dr. Kumar said. Get the burned area under room temperature running water (it may be easiest in the bath or shower) while you wait for help to arrive. (Don’t use cold or icy water; the extreme swing in temperatures can further damage the skin.) For small burns, run the wound under room temperature water. Then apply a cooling ointment, like aloe vera gel or topical lidocaine, and cover loosely with a large adhesive bandage or gauze.

Change the dressing a couple of times a day, and watch for signs of infection as you would with a cut. Apply antibiotic cream as the initial stinging subsides. Don’t pop any blister that forms; it’s protective, and burns are more prone to infection than the average cut.

Any burn on the face, genitalia, hands or feet (where scarring on joints can limit movement down the road) should get immediate attention, “preferably at a hospital that has a burn unit,” Dr. Cheng said. Doctors now use the terminology “partial thickness” and “full thickness,” as opposed to second- or third-degree, when discussing burns. A partial or full-thickness burn, no matter how small, should be seen. Telltale signs: extreme redness and immediate blistering, weeping (it’s oozing or appears wet) or a burn that looks pale, mottled or deep within the skin.

It’s rare for a sunburn to be serious enough for a hospital visit. You need to, first, get out of the sun; then, apply a gentle moisturizer, cooling gel or aloe vera. Take ibuprofen to reduce pain and inflammation. Don’t pop your blisters. If blisters look infected, see a doctor. And the next time you go out, remember to wear sunscreen — and reapply it regularly.

Most sprains, which are injuries to the ligaments that connect your bones and support your joints, occur from sports or exercise. They typically happen to ankles, wrists and knees. Tweaking backs is also a biggie. “For young children, the bone is softer and more flexible because it’s still growing, so many of these injuries are more likely to be a break than a sprain,” said Dr. Nicole Gerber, associate director of clinical services for pediatric emergency medicine at NewYork-Presbyterian Hospital/Weill Cornell Medical Center.

If you can’t move the injured area at all or if there is a deformity, such as a bump or curve where there shouldn’t be one, go to the hospital, Dr. Kumar said. If you experience constant pain even when you’re not moving, or if there is significant bruising or swelling around the area of the injury, you should also see a doctor, she added. For sprains that don’t fit into these categories, use the R.I.C.E. treatment: Rest, Ice, Compression, Elevation. Ice the area, wrap it with an elastic bandage, take a pain reliever and keep the injury elevated above your heart to help with swelling.

Continue with R.I.C.E., icing for 15 minutes every two to three hours for 24 to 48 hours, or even 72 hours if it’s still swollen. When the swelling has gone down, move the injured area a little — side to side, up and down — so it doesn’t get stiff. “Keeping it wrapped is a gentle reminder to be careful with that body part and let it heal,” Dr. Gerber said.

Determining a break from a sprain can be tricky, especially if there’s no red flag like a finger pointing the wrong way. If there is still significant swelling and pain after a couple of days, and you have a hard time putting weight on the injured area, see a doctor. With children, you may not want to wait that long. “Give a dose of ibuprofen and reassess in one to two hours,” Dr. Gerber said. “Medicine can help with pain and inflammation, but it won’t heal a broken bone.” If pain persists with medication, see a doctor.

Most head bumps are just that: bumps, not concussions. That said, run-of-the-mill goose eggs from falling or banging your head on a cabinet door are treated similarly, even if they are less serious.

First, you need to rule out any signs of concussion; symptoms include loss of consciousness, nausea, vomiting, dizziness or blurred vision. If you are not experiencing those symptoms, lie down with an ice pack and take some acetaminophen. (Steer clear of ibuprofen, doctors say; it can slightly inhibit clotting, which is dangerous if the head injury is severe enough to cause internal bleeding.) If you are on a blood thinner, you should see a doctor to rule out a brain bleed.

Keep resting and taking acetaminophen as needed. Avoid alcohol or other substances that can make a headache worse. That goes for screen time, too.

If you have severe head pain, vomit more than once or are acting confused or experiencing motor or vision changes, head to the E.R. right away or call 911, Dr. Cheng said. If you think it might be a concussion but the symptoms are more mild, take it easy and follow up with your primary care doctor the next day. For any head injury, no matter how small, talk to your doctor if symptoms persist for a week.

Summer in the great outdoors means mosquito bites, bee stings and reactions to pesky plants like poison ivy and poison oak. Most of these do not cause a serious allergic reaction; they’re just annoying.

“Treatment is pretty similar for all things that itch,” Dr. Gerber said. Take an oral antihistamine, like Claritin or Zyrtec. Benadryl also works, but remember: It’s a sedative. Wash the area with soap and water — especially if you’ve been in contact with poison ivy or oak, since oils from the plants can spread on hands or clothing. Apply a topical itch relief cream like calamine lotion or Benadryl cream. Ice can also help calm stinging.

It’s normal to have a red welt and some pain at the site of a sting or bite. Continue taking antihistamines and apply creams to help with itching. Insect stingers do pierce the skin and can introduce bacteria, so watch for signs of infection (such as increased redness and pain, or pus). If you’ve been in contact with poison ivy or oak, make sure to wash any clothes or towels that touched your skin.

Stings become an emergency when they cause anaphylaxis — which isn’t just about having trouble breathing. Anaphylaxis is defined by affecting two or more of the following systems: skin (a rash like hives appearing in an area besides the spot you were stung), respiratory (feeling like your throat is closing, or wheezing), gastrointestinal (vomiting or diarrhea) or cardiovascular (feeling lightheaded or experiencing a fast heart rate). “The most common are reactions with the skin and respiratory systems,” Dr. Cheng said, but people often aren’t aware of the other two.

Dangerous bites like those from brown recluse or black widow spiders come with other symptoms, such as abdominal cramps, headache, or a bite with a blood blister or crater in it, Dr. Cheng said. If you’re bitten and experience any of those, head to urgent care or the E.R. And check for ticks, which can transmit Lyme-causing bacteria or other pathogens. If a bite has a bull’s-eye rash around it, that’s a sign of Lyme; see a doctor.

Doctors recommended stocking these basic supplies to treat minor injuries. They also suggested including a few items that might save a life while help is on the way, like Narcan for overdoses and a tourniquet (crucial if you use power tools). Taking a CPR course and knowing how to perform the Heimlich maneuver are also excellent ways to ensure you’re prepared in an emergency.

A good first aid kit, like this pick from Wirecutter, will include many of the items on this list. Then it’s just a matter of filling in the blanks.