If you take prescription Zantac or other heartburn medications that are part of the worldwide recall announced Tuesday, what are your options? Here are some answers for Canadian consumers.

The heartburn medications in the recall all contain the ingredient ranitidine. It's an acid reducer to lessen the frequency and severity of heartburn. It's also used to treat stomach ulcers.

Health Canada lists 12 affected products that are manufactured with ranitidine and have been voluntarily recalled.

The reason regulators have flagged some ranitidine products is because of an impurity called N-nitrosodimethylamine (NDMA).

The European Medicines Agency said NDMA is considered a probable human carcinogen (a substance that could cause cancer) based on animal studies. NDMA is also an environmental contaminant found in water and food including meat, dairy products and vegetables, according to the U.S. Food and Drug Administration (FDA).

Barry Power, senior director of digital content at the Canadian Pharmacists Association, said the impurity was found in a manufacturing plant used to make prescription versions of the products.

Over-the-counter versions that consumers grab off store shelves themselves are not included.

What to do

"If [consumers] did not get a prescription vial dispensed by a pharmacist, they do not have to do anything because those products in Canada are not affected. If they did receive prescription-strength ranitidine — Zantac is one of the brand names — they should contact their pharmacy," Power said.

Health Canada said people should not stop taking prescribed ranitidine before speaking to their health-care provider because the risk of not treating the condition could be greater than the cancer risk associated with exposure to the NDMA impurity.

What are the alternatives?

Dr. Emily McDonald, an assistant professor of medicine at the McGill University Health Centre in Montreal, said for people with mild symptoms of heartburn, certain lifestyle changes are advised:

Avoid caffeine, chocolate, alcohol and mint.

Elevate the head of the bed to sleep.

Avoid meals before bedtime.

Over-the-counter calcium antacids, such as Tums, relieve short-acting heartburn.

Canadians may also be prescribed ranitidine to reduce stomach acid for the treatment and prevention of various conditions, such as heartburn, ulcers of the stomach and intestines, and gastroesophageal reflux disease (commonly known as GERD).

In those cases, Famotidine (brand name Pepcid) or another class of medication that achieves the same effect on stomach acids are other options.

Power said some pharmacists are reporting short supplies and are doing their best to provide alternatives.

What's the risk?

The impurity was found in the manufacturing process recently, Power said.

"It's probably relatively low risk in terms of causing long-term problems for people," he said.

Australia's regulator, the Therapeutic Goods Administration (TGA), said the additional risk posed by NDMA from ranitidine, at the levels identified to date, is considered to be very low.

"However, such contamination is considered unacceptable for a medicine. The actual health risks depend on dose and will vary from person to person. The risks from short-term use of ranitidine are expected to be extremely low," TGA said.

Similarly, the FDA said although it has detected NDMA in limited ranitidine samples at low levels, "these levels still exceed what it considers acceptable for these products."

What are regulators doing?

The U.S. Food and Drug Administration said a testing method used by a third-party laboratory used higher temperatures and detected higher levels of NDMA from ranitidine products than its own lower temperature method.

A spokesperson for the FDA said Thursday they're "thoroughly investigating levels of NDMA in ranitidine, the source of NDMA and any possible risk to patients."

Health Canada has publicized voluntary recalls by generic companies selling ranitidine-containing medications and said it continues to gather and share information with other regulators and Canadian companies to better understand the issue, including conducting its own tests and informing the public of new safety information.

Regulators in Britain, the European Union and Hong Kong have also issued alerts or recalls.

Has NDMA come up in medications before?

Yes.

Since 2018, Health Canada, other regulators and researchers have worked to address NDMA and similar impurities found in certain "sartan" angiotensin receptor blocker (ARB) blood pressure medications.

Why is this occurring?

Power said the ranitidine and ARB issues point to the fragility of drug supply in Canada and worldwide.

"The lack of redundancy in the manufacturing and distribution processes are causing problems for patients who need these medications," Power said.

Since there are so many vulnerable points along the manufacturing and supply chains, there's no one simple solution.

"It's something that governments collectively can do worldwide with manufacturers."