When Iona first got the blemish, she was irritated, but not too concerned.
She assumed the pimple was the result of a few late nights or some junk food — nothing out of the ordinary.
"But [after a while] I realised that I consistently had this one really bad pimple, and then consistently had a couple of really bad pimples," Iona said.
The acne came as a surprise for Iona, who didn't have a history of acne.
"I never had any problems with acne growing up," she said.
"And I thought that was kind of odd because both my sisters had to go on [prescription acne medicine] in their teen years. I thought that I'd been lucky or blessed with good skin."
But in her early 20s, with no marked change in lifestyle or diet, Iona began to struggle with constant outbreaks of acne around her mouth and cheeks.
"For a while, I assumed it was a phase. But after two years, I decided that 'I have bad skin'," she said.
"I stopped thinking about it as a temporary thing and it became a fixed state."
Now 27, Iona has had acne, at varying degrees of severity, for the past five years.
A lack of information
Iona said when her skin started to get bad, she had very little information about what the term "adult acne" meant.
"I didn't really know what was going on," she said.
"Speaking to my friends, especially my female friends, I found out a couple of other people were in a similar situation.
"But it's a difficult thing to identify, because people approach skin conditions in such different ways.
"Some people think it's just a reflection of your lifestyle or what type of contraception you're on, for example.
"There were so many variables — whether I was on the pill or I wasn't, whether I was eating dairy, whether I was drinking [alcohol] or not."
Half of us have acne into our 30s
In fact, up to half of all men and women experience acne into their 30s, University of Melbourne Professor of medicine Rodney Sinclair said.
There are several conditions that lead to pimples, but acne vulgaris and acne rosacea are by far and away the most common, said Professor Sinclair, also director of dermatology at Epworth Healthcare.
"The classic one we tend to think of when we think 'acne', is called acne vulgaris," he said.
"That's the ordinary, common or garden variety acne that causes pimples in adolescents."
It occurs when there is a problem with the production of oil (sebum) or its flow to the skin surface.
When adults have acne vulgaris, it is sometimes an issue that newly presents itself in adulthood (often in women who have the under-skin contraceptive implant for the first time or in women who stop taking the oral contraceptive).
But more commonly, it tends to be a hangover from adolescence.
"Acne vulgaris is thought to be a disease that lasts for 10 to 12 years. So if you get it at 12, it'll clear up at about 22. But if you get it at 16, then it'll last till you're 26," he said.
"So sometimes acne that persists is just a matter of getting it late."
But acne rosacea "tends to affect women in their 20s and 30s and men in their 40s and 50s" and its cause is unknown, Professor Sinclair said.
It is associated with flushing and redness of the face, and produces papules (blind-headed bumps) and pustules (classic yellow-headed pimples with red rings around them) — but not blackheads or whiteheads, which come with acne vulgaris.
"There are other types of acne that can occur late in life, either through drugs (certain medications cause pimples) or it can occur through hormonal issues like polycystic ovarian syndrome (a problem with the ovaries that also affects fertility, body hair, and skin)," Professor Sinclair said.
The psychological impact
With all these variables, accurate diagnoses can be a difficult game and, for people like Iona, an ongoing process.
"It's been incredibly frustrating. It's been expensive, it's endless," she said.
"I'm still on treatment and not sure at what point I'll be able to come off it."
But above and beyond any inconvenience, it's the psychological impacts of acne that have given Iona the most grief.
"It affects me so much. It's something that I became very self-conscious about," she said.
Iona said her form of acne — a variation of acne rosacea — was especially difficult because its arrival coincided with the age many people first enter the professional job market.
"I felt really embarrassed," she said.
"I'm not someone that likes to wear that much make-up, but felt like I had to wear it every single day.
"But, at the same time, make-up is something that's meant to exacerbate the problem so I felt a sense of conflict.
"I wanted to make my skin better but I was too embarrassed to leave the house without covering it up."
Effective treatments do exist
Although difficult to diagnose at times, effective treatments for acne do exist and, depending on the type you have, are usually not too involved, Professor Sinclair said.
Most treatment attempts begin with what Professor Sinclair called "conservative management".
That involves things as simple as avoiding food you know inflames your acne to changing your bedclothes because you overheat at night — a known cause of acne in adults.
Beyond those treatments, there are a range of over-the-counter creams, prescription antibiotics — both in pill form and applied to the skin — and other prescription medications that have great success.
Iona is now on a combination of the contraceptive pill, some versions of which help reduce acne symptoms, and a topical antibiotic.
"My skin is better, so I've definitely had some relief," she said.
What you need to know about adult acne:
- Usually one of two types: acne vulgaris or acne rosacea
- Acne vulgaris can be hangover from adolescence — thought to last 10 to 12 years
- Acne vulgaris can leave scars but acne rosacea doesn't
- Treatments include medications, a different diet and simple things like changing bed clothes at night
- Nearly half of all adults have acne into their 30s
Does diet impact acne?
- Studies show no strong link with chocolate or lollies
- There's weak evidence a low-GI diet may help (ie eating carbs that break down slowly)
- But you can try cutting foods you feel cause acne
What type of pimple?
- Blackheads — pores blocked by dead cells (which look black)
- Whiteheads — sebum build-up behind blocked pores
- Papules — sebum broken out into layers beneath skin's surface to form painful reddish lumps
- Pustules — classic pimples, with inflammation turned into pus and broken through to skin
- Cysts and nodules — lumps deeper in skin from hardening of tissues left from inflammation
- Open sores — pimples that have been scratched, exposed to air
- Scars — pockmarked, sometimes darkened, skin left after pustules and pimples heal