EVA CHEN YA-PING stood in the shower after her gym workout, horrified: her hands were full of her own hair. 'When I saw my hair falling out, I was shocked - and depressed,' she says. 'I even thought that maybe I had cancer. I'm a very stylish person and I love dressing up and looking good, so I couldn't stand it.' When a friend noticed that her centre parting was looking slightly bald, Chen went straight to the doctor. The 36-year-old Hong Kong housewife has been on hair-loss medication since September. Although her specialist dermatologist doesn't want her on it long term, Chen is worried. 'I'm afraid that if I stop taking it, my hair will start falling out again.' Despite some improvements, Chen's life isn't back on track. She's changed her hairstyle - sweeping hair to the side - but her passions for style and socialising have paled as her anxiety has increased. According to Hong Kong plastic surgeon Walter King and website www.hairdoc.com , hair loss is caused by a variety of factors - some temporary and others permanent, and most usually affecting head rather than body hair. It can be hereditary, particularly on the male side, King says. It's also sometimes caused by auto-immune disorders, with the immune system attacking its own hair follicles. US-based physician Peter Panagotacos - whose book, Hair Loss Answers (Elite Books), can be read free online at www.hairdoc.com - says that although some people think that nutritional deficiencies can cause hair loss, they're rarely the cause. Nonetheless, there is wide marketing of nutritional supplements that claim to enhance hair growth and health. Various poisons (apart from chemotherapy and radiation therapy) and some prescribed drugs can cause hair loss. It's common during the first three months after childbirth. Because less hair falls out during pregnancy, it's catch-up time. Over-zealous hair styling with heat and strong products can also damage hair. Hollywood hair- dressers and other beauty insiders refer to the condition as 'actress hair', says Karen Shelton of Hair Boutique.com. 'Any performer must deal with the reality of what constant hair changes do to the scalp and surrounding tresses,' she says. But none of this applied to Chen. Her hair loss was brought on by severe stress caused by an argument with a close family member. 'In extreme cases of stress, the hair can suddenly stop growing,' says King. 'The hair won't fall out the next morning. It may take a couple of months - although I've seen people go bald in a couple of weeks. Then it may take a year or two to grow back.' Head hair grows in five-year cycles and humans have about 25 to 30 cycles from birth, says King. Losing 50-100 hairs every day is normal, even though it may sound a lot. For most of the five years, hair follicles are active, making hair and sending it down the shaft. After five years, the follicles disintegrate, shifting from an active to a resting phase. Soon afterwards, Panagotacos and King say, hair falls out. Severe stress can make follicles switch to a resting phase prematurely, causing hair loss. Hair-loss medication was the best option for Chen, but others prefer wigs. Tsim Sha Tsui-based Lily Wigs has operated for more than 40 years, and 80 per cent of its clients are women. Some own more than 30 wigs, says store manager Linda Ho. 'They need daytime and evening wigs so they can change their hair just like their dress,' she says. Not all store's customers suffer from hair loss - some simply want to mask grey hair, for example. Full wigs have a cap into which real human hair (typically from the mainland) is inserted, so they can be hot and heavy. Hair pieces and toupees use grips to keep them in place, and should last about two years, depending on how well they're cared for and how often they're worn. And they're not just for women. 'Hong Kong men are getting balder, younger,' Ho says. 'Mainland Chinese men don't get so bald. Perhaps it's because here men are so stressed and overworked.' Central-based dermatologist Tinny Ho agrees that many Hong Kong men are losing their hair. 'You see all these hair-treatment clinics in Hong Kong,' she says. 'Although some topical treatments have scientific backup, not all do. Some men spend thousands of dollars on nonsense treatment.' But between the spam e-mails that promise overnight hair re-growth and the companies offering weird hair cures, there are only two hair-loss medications approved by the US Food and Drug Administration: Propecia for men and Rogaine (also called Minoxidil) for men and women. Propecia is based on an anti-male hormone formula that can affect men's sex drives. 'Research shows that maybe 2-3 per cent of men will be affected,' says Ho. 'But this is reversible once medication stops.' Male pattern baldness, the most common complaint, can be as much a concern for men as cellulite is for some women, experts say. King says it can start after puberty, usually at the crown and temporal areas. As these two areas continue shedding hair, they eventually meet, leaving a border of hair around the back and side of the head. Baldness arises from hair follicles that are genetically too sensitive to a hormone that's linked to testosterone, so even though men's blood hormone levels are correct, the hair follicles in the crown and temporal areas are so over-sensitive that they fall out, King says. 'Prematurely balding men worry that they look too old,' he says. During the hair transplants that King undertakes, a strip of scalp from the back of the head is removed and then sliced into so-called micrographs that contain one, two or three hairs. Small slits are then made in the bald scalp and the micrographs are implanted using fine tweezers. Because the donor hairs from the back of the head aren't hormone-sensitive, they don't fall as easily even after the transplant. The operation takes six hours, during which time the patient is sedated but awake. 'If you have partial hair loss and you're not ready for a hair transplant, hair weaving [hair extensions] is a good alternative,' says King. 'But it's time-consuming, difficult to take care of and has a limited duration of a couple of months.'