These are synthetic fibres that are glued one by one or in small groups to natural eyelashes. They will gradually fall out with the natural lashes.
How bad: If not done properly, the lash extension can cause corneal abrasion, said Dr Sunny Shen, a senior consultant and head of the oculoplastic department at the Singapore National Eye Centre.
Also, the glue that is used to bond the extensions often has formaldehyde or other chemicals that can irritate the eye.
Dr Leo Seo Wei, a senior consultant ophthalmologist at Mount Elizabeth Hospital, said she has seen patients with eye problems due to eyelash extensions. "These can be allergic reactions to the chemicals or other components that make up the eyelash extensions or glue, resulting in eyelid redness, swelling and eye redness," she said.
"In such cases, patients need to get rid of the extensions and start treatment with anti-allergy and anti-inflammatory medication."
There are also cases of patients developing conjunctivitis or eye infections. Dirt and bacteria can get trapped within the extensions.
"As the natural lash grows out, the distance between the sheath of eyelash extension and the skin on the eyelid gets longer and this is an area where debris from makeup, bacteria, dead skin cells and oil accumulates," said Dr Leo.
Other problems can develop if eyelash extensions are used on a long-term basis.
When worn on a regular basis, the weight of the eyelash extensions can put stress on the hair follicle and eventually cause it to fall out and not grow back, said Dr Leo.
This means the user will have fewer natural eyelashes. She may then become even more dependent on eyelash extensions prompting a vicious cycle, she added.
If you are still keen: "There are no fixed rules. As long as the patient understands the risks, keeps the area clean, has no complications, she can continue to have the eyelash extensions," said Dr Leo.
Do have it done professionally by a trusted beautician, said Dr Shen.
These are strands of synthetic or human hair that are attached to existing hair fibres using glue, braids, sewing, or clips.
How bad: Some people are allergic to the chemical or glue used for hair extensions, and this can cause an inflamed and itchy scalp, said Dr Liew Hui Min, specialist in dermatology & consultant, Raffles Skin & Aesthetics.
The weight of the hair extensions can put the scalp and existing hair follicles under constant tension. This will gradually cause the scalp to be inflamed and scarred, and can lead to permanent hair loss, with discrete patches of baldness, she said.
It may take several years before signs of permanent hair loss is noticed, said Dr Liew. But not everyone with hair extensions will experience permanent hair loss.
Dr Liew has had patients who suffered hair loss which surfaced after they started using hair extensions on a daily basis, for a few years.
If you are still keen: Occasional wear should be fine, said Dr Liew. Go for temporary extensions, which can be detached from the scalp easily so they need not be worn to sleep, she said.
POSSIBLE ALLERGIC REACTION
These can be allergic reactions to the chemicals or the other components that make up the eyelash extensions or glue... In such cases, patients need to get rid of the extensions and start treatment with anti-allergy and anti-inflammatory medication.
DR LEO SEO WEI, a senior consultant ophthalmologist at Mount Elizabeth Hospital, on patients with eye problems due to eyelash extensions.
These are done with gel polish. An ultraviolet (UV) lamp is then used to harden the gel polish and bind it to the nail. Gel polish will not chip in a few days, like regular nail polish. But the application and the removal of gel polish can cause brittle and thin nails, said Dr Liew.
How bad: The chemical used, for example, acrylate, can cause allergic contact dermatitis on the skin adjacent to the nails. There is also the possibility of developing a rash on the eyelids when using the hands to rub the eyes. Repeated application of gel manicure can cause permanent scarring and damage to the nails, said Dr Liew.
The UV light used to dry the gel polish may pose a risk for skin cancers, especially for fair-skinned individuals who use the light repeatedly over prolonged periods.
"Unregulated repeated treatments with UV light may theoretically increase risk of non-melanoma skin cancers of the nails," said Dr Liew. "But there has not been a strong link to skin cancers as of now."
If you are still keen: Opt for regular nail polish instead of gel, because the removal of the gel polish will likely damage your nails, said Dr Liew.
Unfortunately, those who have allergic contact dermatitis will continue to experience persistent rash and are, therefore, discouraged from using any nail polish.
Glitter and red make-up
Glitter, which provides an instant glamour effect, can easily be found in make-up and skin care products such as eye liner and body oils. As red is associated with Chinese New Year, some people may want to use red make-up, some of which contains dye made from dried crushed bugs.
How bad: Glitter products are generally safe if you are using most reputable cosmetic brands, said Dr Eileen Tan, a dermatologist at Eileen Tan Skin, Laser and Hair Transplant Clinic, Mount Elizabeth Novena Hospital.
However, if you are unsure of the source, it is better not to try it on your face first but to do a DIY test patch on the forearm or neck region, she said.
Dr Tan said that in general, red pigments in make-up do not get absorbed into the skin, but may cause skin irritation or dermatitis in individuals with sensitive skin.
Many cosmetic products are in one way or another derived from animal or plant sources, she said.
Nevertheless, if your skin is prone to eczema, psoriasis or rosacea, it is best to keep your skin care regime simple.
If you are still keen: Try not to leave your make-up on overnight. If you experience itchiness and redness, remove the contact irritants quickly, said Dr Tan.