What people think it is: So you're feeling like a gangsta, and you go to brush your shoulders off. Imagine your surprise when it's not swag that flies off your shoulder, but ... flakes of dry, dead skin. Cue the cringing. Most people assume this is due to a dry scalp or not washing your hair enough.

What it actually is: Dandruff is actually indicative of the opposite of a dry scalp. The organism Pityrosporum ovale, a yeast-like organism present on our heads, feeds on excess oil and dead skin cells, causing the cells to shed more frequently, which results in those pesky flakes. Some people have an inflammatory reaction to the overgrowth of this organism, which causes the redness and itching.

How you get it: While some people have a genetic predisposition to it, Dr. Krant says that anyone can have dandruff.

How you get rid of it: Dr. Krant recommends shampoos that contain pyrithione zinc, selenium sulfide, coal tar, and ketoconazole. "All of these help to kill the organism and reduce the population so there is less to react to," Krant says. She notes that products with hydrocortisone (one-percent solution) or salicylic acid will help with the inflammatory reaction, but will not address the growth of the organism itself. See our list of the 8 Best Dandruff Shampoos to find a reader-recommended product that's right for you.

For a chronic case of dandruff, you may need to see a dermatologist for a prescription and to rule out bigger health problems that dandruff can be a symptom of, such as seborrheic eczema, an autoimmune condition, or Parkinson's Disease.

How you prevent it: Shampooing more frequently can help keep dandruff at bay because the organism that causes it is drawn to oil for its dietary needs. (Ick.)

What people think it is: Personally, the term "foot fungus" brings to mind the sort of sludge that exists at the bottom of my shower drain. I imagine this disgusting concoction seeping its way under my toenails, resulting in a bacteria-fueled, living, breathing fungus that could take over my body and eat my brain in my sleep.

What it actually is: Foot fungus is caused by a fungus that thrives in damp, confined conditions (so my fears aren't too far off the mark). The same fungus causes toenail infection, and Dr. Krant notes that it's easy to keep re-infecting your feet once your nails are infected. The symptoms include itching and scaly skin, especially between the toes. Blisters and cracked heels may also develop.

How you get it: Contrary to popular belief, walking around barefoot may actually prevent foot fungus. The fungus requires a warm, moist environment, such as the inside of a shoe, to thrive. Most people pick it up in communal showers or by using the towel of an infected person, so bring your own flips to the gym.

How you get rid of it: "Over-the-counter treatments have gotten more effective in recent years, and include formerly prescription-strength antifungal creams," says Dr. Krant. Try Funga Soap by Pedifix for foot fungus, which contains antifungal tea tree oil, and Fungi Nail Antifungal Solution for fungus under the nail. Vinegar soaks (made with one part vinegar and two parts water) can also be helpful for 15-20 minutes daily. Dr. Krant warns that many patients underestimate the length of the treatment for OTC products (standard treatment time is around 12 weeks), and stop the medication before the fungus is completely eradicated. If your feet are particularly sore, or if the rash is spreading, Dr. Krant says it may be a bacterial infection or inflammatory condition that can't be treated with OTC creams. If you're in that number, see a dermatologist.

How you prevent it: Dr. Krant recommends keeping feet as dry and sweat-free as possible. Change your shoes and soaks daily, and allow your feet to breathe. If you're prone to foot fungus, or have particularly sweaty feet, use antifungal foot powders in your socks to prevent reinfection.

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What people think it is: A scarlet letter declaring frequent one-night stands with sleazy strangers.

What it actually is: There's a stigma around cold sores, and it's not entirely without reason. Cold sores are most often caused by herpes virus type 1 (usually associated with oral cold sores) but also by herpes virus type 2 (typically associated with genital herpes).

How you get it: "More than half of Americans have had some kind of exposure to HSV1, and about 15 percent to HSV2," says Dr. Krant. Cold sores are not necessarily sexually transmitted. You can get one from sharing lip gloss or beverages, and you can even contract them in utero. It's a person-to-person communicable disease, so if you come into contact with someone who has it, you can catch it.

How you get rid of it: Once you feel a cold sore coming on (most people describe it as a tingling feeling around the mouth), start treatment immediately with an OTC cream, like Abreva or Orajel. "The faster you are able to start some form of treatment, the shorter the duration of the outbreak should be," says Dr. Krant, who notes that if you're already dealing with a full-blown cold sore, there's not much you can do to make it go away faster. She recommends OTC creams or talking to your doctor about a prescription for pills or cream if you get them every once in a while. If you have frequent outbreaks, you can also talk to your doctor about taking a daily dose of oral antiviral pills, which may suppress outbreaks over the long run. But make no mistake -- just because you can't see it doesn't mean it's no longer contagious.

How you prevent it: "The only way to prevent coming into contact with any form of HSV is to assume everyone you might have contact with has been exposed," says Dr. Krant. While you can ask someone if they have HSV, there's a chance they may not know themselves. It's also possible to be exposed to HSV1 and never have an outbreak. The same goes for HSV2, although it's less likely. Dr. Krant notes that stress, lack of sleep, excessive sun exposure, or anything that knocks your immune system can make a cold sore breakout more likely.

What people think it is: Cancer! A tumor! Another head!

What it actually is: Keloid scars are oddly shaped lumps that form in an area of injury. After they form, they continue to grow outside the area of initial injury. Dr. Krant says keloid scars are distinct because they are made of "neoplastic" benign tumor tissue that grows into the shape of large lumps or irregular shapes. These are not to be confused with a hypertrophic scar, which is a thickened, raised scar that can be red or purple, but never grows beyond the original injury site.

How you get it: "The tendency to form keloid scars is largely genetic," says Dr. Krant. Doctors don't really know why some scars form keloids and others do not, but your chances are greater if you have a family history.

How you get rid of it: Both keloids and hypertrophic scars can be flattened and faded with a silicone gel sheet, corticosteroid injections and lasers. However, Dr. Krant warns that while these treatments may work well on hypertrophic scars, a keloid scar may respond the wrong way and grow even more. Yay. Left untreated, keloids may continue to grow over time. Some keloids, like those received from ear piercings, can be cut off completely. If partially cut off or done incorrectly, the keloid, says Dr. Krant, can grow back larger than before. Word of caution: while researching this story, I saw a YouTube video of someone removing their own keloid scar. Do. Not. Do. This. It's a very bad idea.

How you prevent it: If you know you are prone to keloids, just say no to elective surgical procedures (like body piercings or tattoos) -- it's the only way to avoid developing this type of scarring. Short of covering yourself in bubble wrap and living in a padded room, there's no way to avoid them totally.

What people think it is: When I think of avoiding pit stains, the image of Julia Roberts standing in front of an oscillating fan in a wedding dress in "Runaway Bride" comes to mind. I won't lie -- I've conducted my own swaying "keep cool" ritual in front of a fan before interviews and dates. Can you blame me? Since sweating is associated with nervousness, bad smells and a lack of confidence, having seriously sweaty pits in public is the animal kingdom equivalent of giving yourself up for slaughter.

What it actually is: Excessive sweating is known as hyperhidrosis in the medical world. Sweating is the body's method of regulating the body temperature. When your temperature rises, the hypothalamus tells the body to start sweating. In those who suffer from hyperhidrosis, the central nervous system doesn't shut this sweating off, for reasons unknown.

How you get it: No one knows why some people sweat excessively, but about four million women suffer from the drenching condition. Dr. Krant does warn that excessive sweating can be the sign of a problem:

"Excessive sweating can be, at best, extremely annoying and socially debilitating. At worst, it could be the sign of a tumor. If excessive sweating comes along with excessive redness, a fast heartbeat, gastrointestinal symptoms like diarrhea, or a feeling of anxiety, there could be more to the story."

Diabetes, thyroid problems, certain cancers and infection are just a few of the conditions that can trigger excessive sweating. If you've noticed a change in your normal sweating patterns, sweat profusely when you're not engaged in physical activity, or find that you're sweating all over your body, rather than the normal places like your armpits, head, face, groin, hands and feet, you should see a doctor.

How you get rid of it: Dr. Krant recommends first upgrading your antiperspirant to clinical strength and using a sweat gland-blocking product called Certain-Dri. If that doesn't work, you can ask your doctor for a prescription antiperspirant. If your body is still turning on the waterworks after these issues, you can get injections of Botox to stop localized sweat. Dr. Krant also recommends a new device called Mira Dry, a non-invasive procedure that uses microwave technology to zap (and destroy) the sweat glands in your armpits. In extreme cases, surgery is an option, though Dr. Krant says that this is used more and more rarely due to the risks (skin irritation, weakness of the hand muscles, or surgical complications) involved. She notes that most of these options are not covered by insurance.

How you prevent it: There's no way to stop sweating before it starts, other than the methods identified above. However, you can make it less smelly by avoiding spicy foods like garlic, onions, and curry. Being sweaty is one thing, but being sweaty and stinking like Tandoori Chicken is unbearable. To avoid the telltale dark circles on your clothing, there is such a thing as underarm pads that, yes, are pretty much like maxi-pads for your pits.

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