How to Stay Safe Using Cannabis in Hot Weather

The connection to summer and cannabis products is well-established in culture; think of cannabis-fueled music festival experiences, beach parties, back yard BBQs and those late summer nights. However, while we associate cannabis use with these positive cultural experiences there are physiological factors introduced by the heat which few of us consider when consuming cannabis during hot weather. Thus it is necessary to understand how the physiological interactions of high ambient temperature combined with the physiological effects of THC can create risk that need be understood prior to venturing outdoors into a heat wave.

Dehydration: The Most Overlooked Risk

Cannabis dries out your mouth through decreased saliva production due to activation of the CB1 receptors on the salivary glands. All cannabis consumers experience this symptom to some degree, and for many people, this will be seen simply as an inconvenient side effect. When temperatures rise, however, this becomes a warning sign that you may be losing water from sweating but have a lower than normal sensation of thirst. Therefore, during hot conditions, you can expect to drink less when drinking should be at its highest levels.

• Dehydration amplifies the dizziness and lightheadedness associated with cannabis-induced vasodilation
• It worsens cognitive impairment, reducing the ability to notice and respond to heat stress
• It increases heart rate further, compounding the THC-driven tachycardia
• Severe dehydration in hot conditions can progress to heat exhaustion relatively quickly, particularly with physical activity

The practical response is straightforward: drink water before you feel thirsty, not in response to thirst. In hot weather with cannabis use, a reasonable baseline is 500ml of water per hour of outdoor activity, more with significant exertion. Electrolytes matter too — sweating depletes sodium, potassium, and magnesium, and plain water alone doesn’t fully replace them.

Specific Risks by Setting

Beaches and direct sun exposure:

The sun provides additional UV (ultraviolet) light as well as thermal energy on top of the ambient temperatures that are often warm. Exposure to sunlight also impairs time perception; users may spend hours in direct sunlight and have no idea how many hours it has been since the last time they moved. All three of these conditions will develop at an accelerated rate compared to normal because your mind is focused on something other than what you’re doing. Practical solution: Set up a timer so you know exactly when to take a break from the sun and go into the shade, put on high factor sunscreen prior to your session(s), and always position yourself in such a way as to be able to get into shade quickly.

Festivals and outdoor events:

Crowded music festivals can also increase risk for heat related illnesses by increasing an individual’s heat load through their own body heat from surrounding people; limiting individuals’ ability to replenish fluids (water); increased metabolic heat production as a result of engaging in physical activity such as dancing or simply walking around while at the event; and because most events occur during the evening/night hours, it disrupts normal sleeping patterns which increases the amount of time that the body is unable to cool itself appropriately before temperatures drop enough to allow for cooling.

Indoor spaces without air conditioning:

Cannabis use has been found to cause an increase in appetite, which may be attributed to the effects on hunger hormone ghrelin. Ghrelin stimulates the brain to produce the sensation of hunger. Ghrelin also increases motivation for food. The body produces less ghrelin when there are high levels of insulin and leptin. Ghrelin decreases after eating.

Swimming and water activities:

THC causes impaired coordination, diminished ability to judge distance or “depth” as well as diminished reaction time and a decreased awareness of cold water shock. These acute effects of THC matter in an aquatic setting. An individual who has been drinking alcohol or smoking marijuana (or both) will experience cold shock response — an immediate and involuntary gasp followed by hyperventilation — if he/she is immersed in cold water. This is particularly hazardous when the face is submerged. Water safety organizations have made it clear: you should never swim under the influence of any substance.

Dosing Differently in Hot Weather

Below are some practical changes to reduce risk when using cannabis in hot environments:

• Lower dose than normally used. Both heat and THC have a cumulative effect on your body. Lowering the dose you normally take will help. Take it slower and wait longer before taking another.
• Choose higher-CBD/lower-THC ratios. CBD has been shown to be anxiolytic (anxiety-reducing) and also vasodilate (dilate your veins). This can counteract the potential negative cardiovascular impacts from THC. Products that have a 50/50 ratio of CBD to THC or even higher amounts of CBD could provide relief in extreme temperatures.
• Avoid peak heat times for outdoor sessions. In the united kingdom, peak sun times occur usually between 12 pm – 4pm during the summer months. These are the highest ambient temperatures. Scheduling your session earlier in the day or later would minimize the amount of temperature stress added onto your cardiovascular system due to THC.
• Inhalation vs edibles in heat. There is a delay between eating cannabis and feeling its effects. This delay is increased exponentially when you are experiencing excessive heat. Additionally, people often become impatient with waiting for relief when they are uncomfortable due to heat. Using inhalation allows you to quickly gauge how much is enough. When consuming edible cannabis, you need to be patient as always, but especially so in hot environments.
• Avoid combining with alcohol. Cannabis combined with alcohol while experiencing high temperatures increases dehydration, increases vasodilation, which can lead to decreased blood pressure, and impairs your ability to think clearly about your reaction to heat.

Warning Signs to Take Seriously

There are some common symptoms of heat related illnesses (heat cramps, heat exhaustion, heat stroke) when someone is under the influence of cannabis. These symptoms may be so similar to other common side effects of cannabis, such as a slow heart rate, low blood pressure, nausea, confusion etc., that they could go unnoticed by the user until it is too late. If you experience any of the following symptoms while out in the sun (or during other times when your body temperature increases), take immediate action. Move to a cooler area, drink water, and seek help immediately if the symptoms do not improve or become worse.

• Unusually fast or forceful beating of your heart.
• Dizziness or lightheadedness upon standing.
• Severe nausea.
• You appear confused or disoriented and this feeling appears to be greater than just being “high”.
• You stop sweating. This is a major red flag for heat stroke; it is a serious medical condition.
• Your skin will be extremely hot and dry to touch.

When someone stops sweating due to extreme heat (and has no apparent medical condition causing them to lose their ability to sweat), they have stopped producing enough perspiration to keep themselves cool. At this point, the person has developed a medical condition called heat stroke. Heat stroke occurs when the body cannot produce enough perspiration to lower its core temperature. When the brain overheats due to excessive internal body temperature, it becomes impaired. In severe cases of heat stroke, the brain can suffer irreversible damage.

The Practical Summary

The physiology is real, but none of it is reason to avoid cannabis in summer entirely. It’s reason to approach it the way any informed user approaches any wellness product — with an understanding of how it interacts with the specific conditions you’re in.