What it looks like: A small, red bump that grows into a large, plastic-feeling bull’s-eye after a few days.
How you get it: A tick latches onto your skin and transfers harmful bacteria to you. You’ll notice the bite right away, and the disease can follow.
Treat it: You'll likely need an antibiotic, which will kill the infection, though the rash may take several days to clear up.
See a doc if: As soon as you suspect you’ve been infected or if you notice a tick, see your doctor. Untreated Lyme disease can lead to serious complications in the heart and joints.
Your best defense: Wear long pants and long sleeves if you plan to be in a wooded area. Also use a DEET-based insect repellent, advises Donald Belsito, M.D., a New York City-based dermatologist. If you find a tick on your skin, remove it soon as possible. (After a tick attaches to your skin, it takes 36 to 48 hours for the insect to infect you.) Use tweezers to grab it as close to the skin’s surface as possible. Be sure to remove the whole tick, and then wash the area thoroughly.
Sun Allergies (a.k.a. Photosensitivities)
What it looks like: A red, scaly, and extremely itchy allergic reaction that’s sometimes accompanied by tiny water blisters.
How you get it: Sun exposure triggers an allergic reaction to certain chemicals, like those founds in medications, in the body. A similar allergy—polymorphous light eruption (PMLE)—is caused by a direct sensitivity to the sun’s UVA rays, and according to dermatologists, your genetics are probably to blame.
Treat it: Oral antihistamines and anti-itch creams will help relieve symptoms, but if you suspect you have a sun allergy, getting the right diagnosis from your doctor can help you avoid the allergy triggers in the future. PMLE may require stronger prescription medication.
See a doc if: Symptoms don’t go away within a week. You likely need a stronger, prescription-strength cream (or for extreme cases, an oral steroid, like prednisone).
Your best defense: Though your doctor or pharmacist should warn you if a prescription drug can cause a sun allergy, keep an eye out for these common culprits: ketoprofen (found in some prescription pain meds) or tetracycline, doxycycline, or minocycline (all found in antibiotics). And, of course, lather on the broad-spectrum SPF.