School’s almost out for summer — it’s time to head to the beach. But beach days aren’t always fun in the sun. Stings, scrapes and burns have the potential to sideline anyone and can even be dangerous enough to warrant an emergency room visit.

I GOT STUNG BY A JELLYFISH (OR MAN-OF-WAR)!

Box jellyfish are known to swarm Oahu’s south-facing shores every month, usually eight to 10 days following the full moon. Portuguese man-of-wars can blow near shores during periods of sustained tradewinds. Both deliver a powerful sting, so heed warning signs and watch out for their clear or blue-tinted bodies and tentacles along the sand.

If you are stung, rinse the affected area with fresh water, not seawater, and pluck (don’t scrape) tentacles off the skin. Jellyfish stings can be treated with vinegar, which helps deactivate the stinging cells; skip this step for man-of-war stings, which are aggravated by vinegar. Urine, a common folk remedy, is not considered effective for either type of sting. Finally, while it might seem counterintuitive, apply heat instead of ice for 45 minutes to treat the area. Visit the lifeguard shack, where vinegar and hot packs are usually available.

In rare cases, jellyfish or man-of-war stings can cause a life-threatening allergic reaction. Call 911 if you experience difficulty breathing, lightheadedness or confusion.

I STEPPED ON A WANA (SEA URCHIN)!

Wana hide in the crevasses of rocks and coral. Their spiky spines can be an unpleasant surprise for swimmers who happen to place their foot in the wrong spot underwater. The spikes are made from calcium carbonate and are extremely difficult to remove using tweezers. They often break apart, leaving parts of the spine embedded under the skin.

Again, vinegar can help. Soaking the foot or affected area in vinegar helps to dissolve or break down the spikes. Intense pain and redness that gets worse instead of better can indicate an infection, so monitor your wound over the next week and seek medical attention if necessary.

I CUT MY FOOT ON CORAL!

Coral is beautiful to look at, but be careful not to touch: It can endanger the reef’s fragile ecosystem, and coral’s sharp edges can cut or scrape skin. If skin is broken, coral can leave trace amounts of bacteria, animal protein and calcareous material in the wound that must be thoroughly cleaned to avoid a nasty infection. Even the smallest cut should be flushed with plenty of fresh water, cleaned with diluted hydrogen peroxide (a mixture of 1 part water to 1 part hydrogen peroxide) and treated with an antibiotic ointment for several days until the wound begins to heal.

If the wound’s edges become red and ooze pus, or you develop red streaks leading up the extremities, seek emergency medical help immediately. These could be signs of a dangerous and potentially deadly infection that must be treated as soon as possible.

I GOT A SUNBURN!

It’s important to protect your skin from the sun’s damaging rays. If you do get a sunburn, there are a number of home remedies that can help minimize your discomfort, such as aloe, cool baths and moisturizing lotions. Sunburns cause you to lose fluids from your skin quickly, so drink lots of water to avoid dehydration.

Sunburns seldom require medical attention, but they can sometimes be accompanied by heatstroke or heat exhaustion. Dizziness, confusion, a rapid pulse and rapid but shallow breathing are warning signs of dangerous overheating. Move the affected person to a cool place and give them fluids until help arrives.

If you run into any trouble at the beach, head to the lifeguard stand. They’re trained to treat minor stings and scrapes and know when a situation requires medical attention. When in doubt, err on the side of safety and always call 911 if someone is experiencing difficulty breathing, severe pain or loss of consciousness. Let’s all stay safe and healthy this summer.

Dr. Gregory Strongosky is chief of emergency medicine at Kaiser Permanente Moanalua Medical Center.