The hidden dangers of Halloween
They're the Hollywood blockbusters that have left movie fans equally terrified and thrilled.
And with their garish make-up and unsettling eyes, they're this year's most popular Halloween fancy-dress characters.
The Joker - as portrayed by Joaquin Phoenix - and Pennywise, the evil clown from the latest adaptation of Stephen King's classic horror novel It, are this year's biggest trending costumes. But as the extraordinary popularity of Halloween in Australia soars, horror enthusiasts are being warned there are risks when it comes to dressing up on October 31.
Health experts have pointed to the hidden side effects of the novelty contact lenses and cheap make-up that are being snapped up by Halloween fanatics for their fancy-dress costumes.
Optometry Australia's Chief Clinical Officer Luk Arundel told News Corp Australia novelty contact lenses were often marketed to teens and young people who were unlikely to be aware of the dangers.
"There is a legal loophole in Australia surrounding the sale of contacts that are not prescription lenses.
"Contact lenses aren't toys," he said. "They need to be prescribed and handled with care and the users need to properly instructed how to use them in order to avoid contamination.
"The biggest risk is when a person goes to bed still wearing the contact lenses, which can often happen after a big night such as a Halloween party."
Mr Arundel, who specialises in the fitting of contact lenses at the University of Melbourne, said complications arising from the use of novelty lenses include inflammation, burning, stinging, discharge and pink eye.
The most serious risk to a user is an eye ulcer, which can scar the clear part of the eye and permanently affect the sufferer's vision.
Costume contact lenses are made from inferior materials, he said, which can impede the flow of oxygen to the eye.
Halloween fans wanting to recreate Joaquin Phoenix's heavily made-up face in Joker also need to be aware of the risks.
Mr Arundel said the use of hypo-allergenic make-up that is kind to eyes and skin is "definitely a plus".
He also warned against glitter, which can get lodged in a person's eye, and cheap false eyelashes, which can cause allergic reactions.
He urged anyone with an issue to visit their local optometrist so the problem could be managed in the early stages and warned against "trying to soldier on".
The warning comes as Australians go all-out with festivities surrounding - an event that ten years ago wasn't even on the average Aussie's radar.
Manager of Melbourne institution Creative Costumes Dale Pruser said this year's big costume trends for parties and trick or treating are "pop culture driven".
Sales of costumes, wigs and prosthetics have soared due to the boom in Halloween-related parties and events.
Aside from the Joker and Pennywise, other popular choices include characters from the Netflix hits Stranger Things and Money Heist.
Retail giants Woolworths and Coles are also cashing in on the trend.
This year Woolworths is expecting to sell more than 200,000 kilograms of Aussie-grown pumpkins nationally, 20 per cent more than last year.
Coles is predicting it will sell 260 tonnes of Aussie carving pumpkins, with many customers pairing their pumpkins with carved Aussie pineapples and watermelons.