These pictures may look like an attractive woman in her 20s and her grandmother.
But they are said to be the same person – apparently taken just days apart.
Nguyen, 26, says she developed this puffy face and sagging skin in 2008 but was too poor to seek treatment. Earlier this month, doctors said they would examine her free of charge.
She has always worn wear a mask in public to hide her appearance from prying eyes, but she has now sought help from doctors to see if they can reverse the "ageing" effect.
Mrs Nguyen believes her condition was caused by a life-long allergy to seafood.
She said she had suffered a particularly bad reaction in 2008.
"I was really itchy all over my body. I had to scratch even while sleeping."
Phuong said she took some medicine bought at a local pharmacy instead of going to the hospital because her and her husband Tuyen, now 33, were too poor to afford it.
She said: "After one month of taking the drugs, I became less itchy but hives remained on my skin."
"Then I switched to traditional medicine and all the hives disappeared, together with my itching. However, my skin began to sag and fold."
Mrs Nguyen then took another kind of traditional medicine to treat her rapid-aging skin problem - but to no avail.
Doctors say it may have been the long-term use of traditional medicines that caused the condition as they are often spiked with corticoids. These steroids speed up the effects of the unregulated remedies but could also have triggered the rare skin disease mastocytosis, where the body produces too many mast cells.
On October 2, doctors from Nguyen Dinh Chieu Hospital in Ben Tre Province said they would examine Phuong for free and send her to the HCMC Dermatology Hospital if they failed to diagnose her condition.