Think hair loss is a strictly male problem? Then I guess your shower drain looks pretty different from mine. Turns out, ladies can’t catch a break: women actually make up about 40 percent of American hair loss sufferers, and 30 million women in the United States have hereditary hair loss (compared to 50 million men). And that’s just hereditary hair loss (aka just due to genetics and aging) — millions more lose strands for other reasons.

If your shower drain looks like a Furby died in it, don’t panic just yet. “It’s normal to lose about 100 hairs per day,” says Dr. David Bank, dermatologist and author of Beautiful Skin: Every Woman’s Guide to Looking Her Best at Any Age. Sounds like a lot, but it’s part of the natural hair cycle, not necessarily the sign of a problem, he says. Dr. Bank’s quick test? “I gently tug on a small section of hair,” he says. “If fewer than five hairs come out in my fingers with each tug, the hair loss is within the normal range.”

If more come out, that’s still not necessarily cause for concern (or a hat shopping spree). Though hair loss can be caused by autoimmune disorders and serious illness, some of the most overlooked causes are actually some of the most likely. Take a look at these surprisingly common hair loss factors:

Your medicine cabinet
Everything from antidepressants and acne medications to beta-blockers and birth control can cause hair loss — a side effect doctors don’t always mention when writing a prescription. Start monitoring your hair as soon as you start taking a new drug so you can act fast. “If you start having hair loss a few weeks after starting a new medication, call your doctor,” advises Dr. Debra Jaliman, a New York City dermatologist.

Stress
In the middle of a breakup and up for a promotion at work? Don’t underestimate the effects of stress — as stress hormones cause the blood vessels to constrict, hair follicles are deprived of oxygen, minerals, and vitamins, so it’s often a major cause of thinning hair or hair loss, says Dr. Bank. If you think your hair loss may be stress-related, try a biotin supplement, a B vitamin that gives skin, hair, and nails a boost (he recommends at least 2.5 mg each day).

Dieting
That cayenne pepper and lemon cleanse isn’t just super depressing — it’s also bad for your hair if you’re not getting enough protein (a must for strong, healthy strands), iron (which delivers nutrients to the follicle), vitamin C (which helps in the absorption of iron), and zinc, omega-3 fatty acids, and vitamin E (which all help protect and hydrate the scalp). Luckily, it’s a quick fix, and hair usually bounces right back once you correct your diet, says Dr. Jaliman.

Your monthly cycle
You may already know that women often experience hair loss during pregnancy and menopause, but plenty also deal with hormone imbalances or fluctuations during their normal cycles. “Some women may have hair follicles that are particularly sensitive to hormone fluctuations, and may notice that they have increased hair shedding in the second half of their menstrual cycle,” says Dr. Tsippora Shainhouse, a dermatologist and clinical instructor at the University of Southern California. If you’re shedding more in the second half of your cycle, you’re also likely noticing significantly less shedding in the first half, when estrogen levels climb.

Your hairdo
If your everyday ‘do gives Ariana Grande a run for her money, try giving the elastic ties a rest and see if your hair starts looking fuller. “If you pull your hair very tightly in braids or a tight ponytail you can get what’s called traction alopecia,” says Dr. Jaliman. “This is because too much pressure and stress is on the hair follicles and destroys them.”

Your heat-styling gear
Your straightener, blowdryer, and curling iron do a number on your strands too. The 400-degree setting is definitely too high, period, Dr. Jaliman says — look for tools with an adjustable heat setting and keep temperatures below 350 degrees, especially if you have fine hair. Also, a diffuser and styling products with silicone will distribute heat more evenly and protect the hair, offsetting some of the damage.

Bottom line? Hair loss can be a hairy situation to figure out, and fixes can range from diet and hairstyling tweaks to topical solutions like Rogaine, depending on cause and severity. If you’ve been shedding for a while, losing a lot more than usual, and aren’t seeing regrowth, don’t attempt a DIY treatment — get your mane to a dermatologist for diagnosis, treatment, and the return of good hair days.

Diana Vilibert is a freelance writer and copywriter living in Brooklyn, NY. She loves flea markets, martinis, to-do lists, traveling, and wearing leggings as pants. You can see more of her writing at www.dianavilibert.com and follow her on Twitter at @dianavilibert.