HE woke up at 4 am feeling some discomfort around his eyes.

When he switched on the bathroom light and looked in the mirror, he got a fright.

His face was puffy, and the area around his eyes was so swollen that his eyes looked like two slits.

Said Mr Pang Chee Leong, 32, a contractor: 'I was shocked when I saw myself. I looked like an alien from a horror movie.'

As he suspected, it was an allergic reaction to some medicine he had taken before going to bed.

Mr Pang was aware that he is allergic to paracetamol and another painkiller, but he had not been prescribed either of them when he had visited a neighbourhood clinic at 8pm for a sore throat and fever.

'I was frightened because I had difficulty opening my eyes and the swelling affected my vision,' said

Mr Pang, about the incident, which happened recently.

He quickly took a cab to a 24-hour clinic where he said he was given an injection and some anti-allergy medicine.

Two days later, when The New Paper spoke to him, there was still some swelling on his face.

The doctor at the neighbourhood clinic said Mr Pang had been attended to by a relief doctor who did take note of his allergy.

She noted that the patient had an upper respiratory tract infection and was prescribed four medicines that would not react to his known allergies.

'Some people, though they are allergic to a certain painkiller, are able to take other painkillers,' she said.

She said it was important for the public to be aware of allergic reactions and inform their doctors, as severe allergic reactions could be fatal.

Dr K V Ratnam, a dermatologist who runs his own practice and specialises in allergies, confirmed that the four medicines the clinic said it had prescribed are not related to the painkillers Mr Pang was known to be allergic to.

'Unfortunately, a person who has an allergy is more prone than other people to develop multiple allergies,' said Dr Ratnam, who is in his 50s.

'Because the immune system is hyperactive to one chemical, it is prone to reacting adversely to other chemicals though they may not be related,' he explained.

DETECTIVE WORK

To find out what the allergens are requires quite a bit of detective work, like allergy testing and evaluating the patients' medical history, said Dr Ratnam.

A comprehensive test to determine what a person is allergic to could take several weeks.

'Allergies can be developed at any one time. A person who has taken a particular medicine before without any problems may develop a new allergy to it,' said Dr Ratnam.

'It's hard to determine the allergens without comprehensive testing.

'Allergies could also be caused by food, or even eye drops,' he said.

Some common allergic reactions are itchy rashes, swelling of the lips and eyes, mouth ulcers, or peeling skin.

He said in severe cases, an allergy could cause asphyxiation due to the swelling of the throat and vocal cords.

'Patients must tell their doctors what medicines they are allergic to if they have a past history.

'But then, nobody can predict what other allergies a person may have or develop until he tries the medicine,' said Dr Ratnam.

This story was first published in The New Paper on Mar 29, 2008.