Hair extensions, originally the domain of the rich and famous, have become increasingly popular with young women the world over in recent years, as they can add length and volume to otherwise lifeless locks.However, with supermodel Naomi Campbell and singer Britney Spears displaying obvious bald patches on their scalps in recent photographs, doctors are now warning that hair extensions could be doing serious damage.The opposite of the desired effectWomen choose to have hair extensions to create the effect of a voluminous mane of hair, but it seems the procedure could be having the opposite effect – causing them to lose some of the hair they already have, and leaving bald patches and thinner areas.Hair extensions are attached to the roots of your existing hair using various techniques and the specific technique depends on which type of extension you’re having fitted.• A partial or full weave is sewn into your own hair • Extensions are bonded with glue to your hair • Clip-ins – the quick and temporary option, these are just clipped underneath the top layer of your hairBecoming a headacheMany women complain of blinding headaches caused by their hair extensions – if they are attached too tightly or are too heavy, this can put too much strain on the hair follicles. This can cause severe, crippling headaches – some extension wearers have undergone MRI scans to find a reason for the pain, before finding their hairstyle was causing the problem – but can also be the reason for hair loss. Often the follicles are stretched so far that the hair falls out, and the damage can be permanent, meaning hair will never grow back. This problem is known as ‘traction alopecia’.How to do it safelyIf you do want to have hair extensions put in, but don’t want to suffer from any of the associated health problems and hair loss, it is important to tread with caution. Do your research – look online and ask friends who’ve had hair extensions before – and choose a salon that you know to be reputable.Once you’ve chosen your salon, book a consultation appointment before going ahead with the hair extensions themselves. Ensure you are happy with your hairdresser and with the technique she will use to attach the extensions – most methods have their pros and cons, and s/he should explain this to you in full, and be able to tell you which technique would be most suited to your specific hair type and why.If you do go decide to go ahead with the extensions, here’s some top tips on how to prevent hair loss:1. Prepare your scalp – make sure your hair is as healthy as possible and avoid over-heating, styling and dyeing it with chemicals in the run-up to having your extensions are put in. 2. Get rid of dandruff – seborrheic dermatitis is much harder to treat when you have extensions in and can cause your hair follicles to become inflamed if not treated properly. Use a medicated shampoo to tackle dryness and flakes, but if it doesn’t clear up then see a dermatologist. 3. Keep it loose – this is down to practitioner choice. If your extensions are put in too tight it can put too much tension on the hair follicles. If they feel too tight when they’re being put in, then speak to your stylist. 4. Follow aftercare advice – gently shampoo your hair once a week or whenever advised by your hair stylist. Then towel dry and comb gently. 5. Replace regularly – even if your extensions are looking healthy, don’t make the mistake of trying to prolong the time between your appointments. Once your extensions are removed – gently – then your stylist can make sure the head and scalp is squeaky clean before deep conditioning the hair 6. Take a break – you might have got used to the appearance of a full head of hair, but it’s important that you let your hair rest every once in a while.