HAMMONDS PLAINS, N.S. -- A Nova Scotia breast cancer patient is raising a red flag about a multi-national shortage of a common cancer drug used by thousands of patients.

Wendy Ackerley has been taking the drug for the past two years and couldn't believe what happened when she went to refill her prescription last week.

"The pharmacist informed me that they had no Tamoxifen, so of course, I was shocked," said Ackerley.

Shocked -- and worried -- because Tamoxifen is a drug commonly prescribed to breast cancer patients like Ackerley to prevent the cancer from recurring.

Ackerley says the pharmacist managed to find a supply outside of the Halifax area, in Hubbards, N.S.

"That pharmacist was actually able to fulfill one third of my prescription, enough to get me through a month," said Ackerley.

She's now calling around to try to get the rest.

"It's a fluid situation," said Dr. Drew Bethune, medical director of the Nova Scotia Cancer Care Program. "We have an anticipated shortage. There are some pharmacies that are short of it right now."

Bethune says the organization heard about the problem early last month, and since the organization doesn't know exactly who takes the drug, it couldn't notify patients, and it chose not to make a public announcement.

"We really were not sure this would ever develop into a shortage and we were worried about creating panic," Bethune said.

But, Bethune says the organization has been communicating with doctors and pharmacists -- and monitoring the supply.

He says patients can go for several weeks without the drug, which buys some time.

"We're trying to only supply only one month's supply of drug at the time, so we can spread out what we have," Bethune said.

According to a recent study published by the C.D. Howe Institute, medical experts say Canadians have been dealing with 1,000 drug shortages every year since 2010.

"It's terrifying to think about not taking it, and what the consequences of that are," Ackerley said. "In Canada this is not acceptable.

Ackerley wants to see drug shortages like this end, so no one ever has to face the possibility of having to go without their medication.

Bethune says the federal government is working on getting a supply from outside the country and that it is also trying to find alternatives, although there is really no drug equivalent.

The Nova Scotia Cancer Care Centre has set up a Tamoxifen information line to answer patients' questions: it's 1-844-989-1502.