nosebleed after smoking weed

Marijuana makes blood rush to the head

Smoking marijuana can affect blood flow in the brain so much that it takes over a month to return to normal. And for heavy smokers, the effects could last much longer, a new study suggests.

Regular marijuana use can harm memory and the ability to make decisions, according to Jean Cadet at the National Institute on Drug Abuse in Baltimore, Maryland, US. To find out why, he monitored the flow of blood through the brains of 54 marijuana smokers, among whom the heaviest user smoked 50 joints every day.

People who smoked cannabis had higher blood flow through their brains than non-users. Yet there was also greater resistance to the blood flow, suggesting that cannabis changes the blood vessels in the brain in a way which hinders oxygen in reaching the tissue effectively. In an attempt to compensate, extra blood is sent to that part of the brain, increasing resistance but probably failing to get enough oxygen through the vessels, Cadet suggests.

Cadet and his colleagues used an extremely sensitive non-invasive technique called transcranial Doppler sonography to “see” the blood flow through individual arteries from the head’s surface.


After a month without cannabis – during which the volunteers agreed to remain in a clinic, with no access to marijuana – Cadet repeated the sonography. The resistance to blood flow of light and moderate users – who usually smoked an average of 11 and 44 joints per week, respectively – was starting to return to normal.

Neuropsychological problems

But there was no improvement observed in the heavy users, who smoked an average of 131 joints per week. “We were surprised because we’d expected that as marijuana cleared the system things would improve,” says Cadet. He now wants to see if there is a link between the changes in the brain’s blood flow and the extent of neuropsychological problems.

To eliminate the effect of tobacco in the joints, Cadet compared his results to those obtained from smokers, who showed normal blood flow. But, says William Notcutt of James Paget Hospital in Norfolk, UK, the longer-term effect on the brain may not have been caused by the same substance that produces the high.

“Somebody smoking 50 joints per day is getting a huge number of carcinogens from the marijuana plant,” he notes. “We know the cardiovascular effect [of cannabis] is very complex and multi-factorial so it’s not as simple as with other drugs. The group that needs to be studied now is people that use high quality medicinal extracts.”

He adds that the results may also be different for people that only smoke marijuana occasionally, and so are exposed to lower doses of the toxic substances.

Journal reference: Neurology (vol 64, p 488)

Smoking joints can affect blood flow in the brain so much that it takes over a month to return to normal, with heavy smokers the worst off

Fake pot users suffer brain bleeding, bloody urine, Illinois health officials warn

Severe nosebleeds, bloody urine and blood on the brain are all symptoms of synthetic cannabinoid products, Illinois Department of Public Health says. (Photo: Chalabala, Getty Images/iStockphoto)

The Illinois Department of Public Health is warning people about disturbing symptoms of using fake pot or marijuana after reports of severe bleeding.

At least 32 people who reported using synthetic cannabinoids since March 7 suffered severe bleeding, IDPH said in a statement this week.

Fake pot is not made up of one drug, but rather hundreds of unknown, unregulated chemicals IDPH spokesperson Melaney Arnold told USA TODAY.

The drug has caused blood in urine, bloody noses, bleeding gums, higher menstrual flows and bleeding into the brain, Arnold said. Another possible symptom is bleeding from the eyes and ears.

While there have been no reported cases of death, Arnold said symptoms can be life threatening.

“At this time, IDPH is not reporting any deaths, but that may change,” she said.

IDPH warns contaminated products could be sold across the state in convenience stores and from dealers.

Cases were reported in eight Illinois counties. Tazewell County near Peoria reported 10 cases, the most of any county. Chicago County had eight, Peoria County had six and Cook County had four.

“Synthetic cannabinoids are unsafe,” Arnold said. “People who have used these products and develop any bleeding issues or have concern about any health effects should seek immediate medical attention.”

Fake marijuana or weed has caused at least 32 people to bleed severely, the Illinois Department of Public Health warns.