If it happens to you, keep calm and follow these simple rules.

One minute you're swimming, just paddling along, when you feel a sharp burning sensation against your leg or arm. Chances are, you've been stung by a jellyfish. Unfortunately, during the hot summer months, conditions are just right for these roving sea creatures.

First, get out of the water and assess the damage. Any portion of the tentacles still adhering to the skin should gently be removed with tweezers. They contain very fine barbs and that's where the venom is.

Next, treat the affected area if it burns, itches, or has discolored the skin. Contrary to the old wive's tale (and a popular Friends episode!), you shouldn't urinate on the site of the sting. You're better off taking a hot shower for at least 20 minutes if possible, according to the Mayo Clinic. Whatever you do, don't scrub or harshly rub the site—you could easily make things worse by breaking the skin.

Most importantly, watch for symptoms of complications from the jellyfish venom. Blisters, nausea, headache, heart problems, and difficulty breathing are just a few of the signs you should look for after the hot shower. Seek immediate medical attention if you experience any of these symptoms in the hours after the injury.

With a little bit of pre-planning and quick treatment, a jellyfish sting can quickly become nothing more than a fleeting memory. Avoid getting stung by heeding posted beach warnings—most manned lifeguard stations will indicate if large blooms of jellyfish have been spotted. They can come in very close to the shoreline, so be on the lookout.

You can also protect yourself by wearing a rashguard type of top or partial wetsuit to cover up. They're available almost anywhere bathings suits are sold.