Parents of children suffering from difficult-to-treat forms of epilepsy are angry that shipments of the hemp oil they rely on to control their children’s seizures are being seized by Canadian border agents.

The families of 19 hemp oil users say the Colorado manufacturer of one type of oil called Charlotte's Web informed them last month they are no longer taking Canadian orders because so many shipments are getting stopped at the border.

Canada Border Services Agency says it is obligated to seize the packages because marijuana and all its derivatives remain illegal in Canada. Health Canada says Canadian families can use made-in-Canada marijuana oil instead, or apply for an exemption under the Controlled Drugs and Substances Act.

But the parents say Canadian companies do not make a product comparable to the Charlotte’s Web oil they import from Colorado, where marijuana was legalized in 2014.

The oil is named after a five-year-old Colorado girl with epilepsy whose condition improved after being treated with marijuana oil.

Users say they prefer it because it has very low levels of THC, the psychoactive ingredient in marijuana, but is high in CBD, or cannabidiol, a substance shown to reduce epilepsy activity.

Alex Repetski uses a marijuana oil he creates in his Thornhill, Ont., home for his four-year-old daughter, Gwen, who has severe epilepsy that has left her developmentally delayed.

While he doesn’t use Charlotte’s Web, his homemade oil has kept his daughter seizure-free for 20 months now and he’s angry that a drug that so many other parents rely on is being taken away.

“I take issue with border agents seizing this product,” Repetski told CTV News Channel Thursday. “There are many people using this product, which is a high-CBD hemp oil, very effectively.”

Repetski says CBD has no psychotropic effects and shouldn’t be banned under the Controlled Drugs and Substances Act. He says for kids who have to stop taking the drug to control their seizures, “the effects are therefore catastrophic.”

One of those children is four-year-old Kyla Williams, who also has developmental delays. She used to have hundreds of seizures a day, but after she started using Charlotte’s Web, the seizures now occur weeks apart.

Williams’ grandmother, Elaine Neussle, is angry that Border Services agents are confiscating the drug her granddaughter relies on.

"I can just see all these little bottles of Charlotte’s Web sitting somewhere in CBSA offices and this is precious oil. This is precious for these children,” she told CTV Vancouver.

Williams` pediatrician, Dr. Manoj Parameshwar, says the confiscation of the oil has created "a potentially life-threatening situation" for Williams.

Nineteen Canadian families have sent letters to the federal government, pleading for border agents to be allowed to let in the oil shipments

“They well know our situation and we have not had a response,” Neussle said.

The CBSA maintains it is illegal to import or export marijuana derivatives, regardless of their intended use.

With a report from CTV Vancouver’s Kent Molgat