At Blakes Pharmacy in Potts Point, store manager Kim Wood watches and waits. The tourist buses arrive, regularly, with keen shoppers who will "buy whatever Blackmores (vitamins) we have".
"Sometimes I come in and the whole shelf has disappeared and getting in stock has been hard to get for close to a year now," Ms Wood said.
"I just did an order and there are four or five things out of stock that I couldn't get my hands on."
Among tourists, Ms Wood said fish oil, cranberry capsules, vitamin C and the eye supplement Macu-Vision were the most in-demand products.
Ms Wood's difficulty in restocking is replicated at some other independent pharmacies from West Pymble, to Strathfield and Kings Cross.
They claim they are struggling to stock their shelves with the popular products due to low warehouse supply.
"I have been complaining for 12 to 18 months now," said Bev, who asked not to use her surname, and handles Blackmores orders for Price's Pharmacy in West Pymble.
"I think because we are an independent pharmacy we are being given much lower priority ... my dilemma is that every time I want stock, I'm told it has run out at the warehouse."
At the Strathfield Boulevarde Pharmacy, store manager Karen Koenig said it can be several months before she is able to replace a certain line of Blackmores products.
"It's not just Blackmores. It is really all the popular lines by Australian companies, mainly in the natural medicine categories," Ms Koenig said.
"Local independent pharmacies feel we are not being supported by Australian companies when we support their brands. Most of their attention goes to the overseas market and also the Australian big players."
Ms Koenig said that large discount chemists who order entire pallets of one product appear to come first when stock is distributed.
"Often we can't even get one box to service our customers ... and it will be like that for weeks and months. We get pushed right down the bottom and yet we are the ones servicing local Australian customers."
Overseas, Blackmores has enjoyed terrific success, largely in China, where high demand for vitamin products saw the company more than double net profit to more than $100 million in the 2016 financial year.
However its share price has tumbled 48 per cent from last year's record high of some $220, as sales have slowed.
Blackmores managing director for Australia David Fenlon said that discount chemist chains were "absolutely not" given priority over smaller outfits.
"All retailers are also offered the opportunity to lodge back orders with us and receive their inventory as soon as the product comes back into stock."
Mr Fenlon said demand from Chinese consumers did impact supply 18 months ago, but since then the company had doubled capacity, leaving it better able to meet the needs of retailers and consumers.
From the pharmacy he manages in Mona Vale, on Sydney's northern beaches, Matthew Feros said there is little he can do as a small operator but "suck it up".
"I look on my shelf right now and I've got 21 empty spaces, which is 10 per cent of my usual Blackmores items out of stock."
Mr Feros, who manages the Gateway Pharmacy in Mona Vale and owns Pyrmont Pharmacy, said in some cases he will go to Coles to buy vitamins in bulk, because it can be $2-$3 cheaper than what he is offered and it is always available.
"We basically have to buy 200 or so of a product, which a small store would never sell and would go out of date, just to get a discount."
He said consumers often visited his pharmacy for advice only, before heading to a discount chemist to make their purchase.
Fairfax Media also contacted pharmacies in Newtown and St Ives who said they had not had any difficulty maintaining Blackmores stock.