Effects of cannabis

[17] When cannabis is smoked, blood levels of THC peak rapidly after a few minutes and then decline, although the psychotropic effects persist for longer.

[citation needed] The rise of edible cannabis products has been responsible for a large increase of poisoning of children and young people.

[18] Synthetic cannabis is suspected of being a potential contributory factor or direct cause of sudden death, due to the strain it can place on the cardiovascular system, or because of cannabinoid hyperemesis syndrome.

Professor David Nutt, a UK drug expert, points out that the study cited by the British Lung Foundation has been accused of both "false reasoning" and "incorrect methodology".

[35] With oral ingestion, however, the onset of effect is delayed, taking 30 minutes to 2 hours, but the duration is prolonged due to continued slow absorption.

This agonism of the cannabinoid receptors results in changes in the levels of various neurotransmitters, especially dopamine and norepinephrine, which are closely associated with the acute effects of cannabis ingestion, such as euphoria and anxiety.

[39] Cannabis produces many other subjective effects, including increased enjoyment of food taste and aroma, and marked distortions in the perception of time.

At higher doses, effects can include altered body image, auditory or visual illusions, pseudohallucinations, and ataxia from selective impairment of polysynaptic reflexes.

[42] Furthermore, even in those with no family history of psychosis, the administration of pure THC in clinical settings has been demonstrated to elicit transient psychotic symptoms.

[43][44][45][46] Any episode of acute psychosis that accompanies cannabis use usually abates after six hours, but in rare instances, users may find the symptoms continuing for many days.

[52]Some of the short-term physical effects of cannabis use include increased heart rate, dry mouth, reddening of the eyes (congestion of the conjunctival blood vessels), a reduction in intra-ocular pressure, muscle relaxation, and a sensation of cold or hot hands and feet.

[59][60] A 2015 study suggests that cannabis triggers uncharacteristic behaviour in proopiomelanocortin (POMC) neurons, which are usually associated with decreasing hunger.

[74] Researchers reported in the International Journal of Cardiology, "Marijuana use by older people, particularly those with some degree of coronary artery or cerebrovascular disease, poses greater risks due to the resulting increase in catecholamines, cardiac workload, and carboxyhemoglobin levels, and concurrent episodes of profound postural hypotension.

[76] A 2008 study by the National Institutes of Health Biomedical Research Centre in Baltimore found that heavy, chronic smoking of marijuana (138 joints per week) changed blood proteins associated with heart disease and stroke.

[77] A 2000 study by researchers at Boston's Beth Israel Deaconess Medical Center, Massachusetts General Hospital, and Harvard School of Public Health found that a middle-aged person's risk of heart attack rises nearly fivefold in the first hour after smoking cannabis, "roughly the same risk seen within an hour of sexual activity".

[82] Of his studies on cannabis use, lead researcher and Harvard professor Harrison Pope said he found it is not dangerous over the long term, but there are short-term effects.

From neuropsychological tests, Pope found that chronic cannabis users showed difficulty with verbal memory in particular for "at least a week or two" after they stopped smoking.

[83] Researchers at the University of California, San Diego School of Medicine failed to show substantial, systemic neurological effects from long-term cannabis use.

[84] The research team, headed by Igor Grant, found that cannabis use affects perception but does not cause permanent brain damage.

[85] A study by Johns Hopkins University School of Medicine found that heavy cannabis use is associated with decrements in neurocognitive performance even after 28 days of abstinence.

[88] The British Medical Journal indicated that "drivers who consume cannabis within three hours of driving are nearly twice as likely to cause a vehicle collision as those who are not under the influence of drugs or alcohol".

[92] An extensive 2013 review of 66 studies of crash risk and drug use found that cannabis is associated with slightly but not statistically significantly increased odds of injury or fatal accident.

Evidence from a controlled experimental study by Lukas and Orozco[100] suggests that alcohol causes THC to be absorbed more rapidly into the user's blood plasma.

Mold is also found in smoke from mold-infected cannabis,[103][104] and the lungs and nasal passages are a major means of contracting fungal infections.

[104] Exposure to cannabis may have biologically based physical, mental, behavioral, and social health consequences and is "associated with diseases of the liver (particularly with co-existing hepatitis C), lungs, heart, eyesight, and vasculature" according to a 2013 literature review by Gordon and colleagues.

The authors cautioned that "evidence is needed, and further research should be considered, to prove causal associations of cannabis with many physical health conditions".

[115][116][117] Cannabis consumption in pregnancy might be associated with restrictions in growth of the fetus, miscarriage, and cognitive deficits in offspring based on animal studies, although there is limited evidence for this in humans at this time.

[118] A 2012 systematic review found although it was difficult to draw firm conclusions, there was some evidence that prenatal exposure to cannabis was associated with "deficits in language, attention, areas of cognitive performance, and delinquent behavior in adolescence".

[119] A report prepared for the Australian National Council on Drugs concluded cannabis and other cannabinoids are contraindicated in pregnancy as it may interact with the endocannabinoid system.

[121] These complications include encephalopathy, hypotension, respiratory depression severe enough to require ventilation, somnolence, coma, and in extreme cases, reports of death.