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What is a ‘weed hangover’ and why does it happen?

June 13, 2017
What Is a 'Weed Hangover' and Why Does It Happen?(MarinaZg/iStock)
For some, it’s a well-known fact while for others, it remains a questionable mystery, but the “weed hangover” is a more common phenomenon then some may think. In fact, it can have a range of effects from brain fog to headache.

To gain a full understanding of the weed hangover, one must explore the limited studies that have been conducted and the symptoms users have experienced, and dispel some of the more common misconceptions that get passed down from one consumer to the next.


5 Frustrating Misconceptions About Cannabis

Cannabis hangover studies

There is admittedly little research when it comes to this topic, which is unsurprising given prohibition’s restrictions on cannabis studies. That said, a few studies exist that can serve as a jumping off point to coincide with anecdotal reports of “weed hangovers.”

The most famous study was published in 1985. Researchers used a very small sample size of only 13 participants to conduct their experiment. The participants, who were notably all men, were given either placebos or joints containing cannabis with 2.9% THC. They were then presented with a number of behavioral tasks after smoking, such as card sorting, free recall, and time production. The subjects were then tested again after a full night’s sleep. Researchers noticed a residual effect in only the cannabis users and stated, “the findings suggest that marijuana smoking can produce residual (hangover) effects the day after smoking. The precise nature and extent of these effects, as well as their practical implications, remain to be determined.”

This study’s results were concluded to be significant (P value < 0.05). That said, there is room for critique due to the study’s small sample size and lack of diversity, leaving definite room for improvement.

Another study from 1998 with a similar sample size of 10 (again, all male) participants studied the residual effects of smoking a single joint and found that “residual effects of smoking a single marijuana cigarette are minimal.” While the results of this study were concluded to be significant, once again, it had a very small sample size lacking in diversity and only looked at the effects of a single joint.

Most anecdotal accounts from users who have experienced a weed hangover report much higher consumption rates, particularly in the manner of RSO and other potent products such as edibles. While there is some evidence to corroborate the anecdotal accounts of those who have experienced a cannabis-induced hangover, more research would be beneficial to truly understanding this phenomenon.


Dosing homemade cannabis edibles: Why it’s nearly impossible to calculate potency

What kind of cannabis products cause hangovers?

As the studies on this topic suggest, a weed hangover (much like other hangovers) is most commonly linked to overconsumption. However, because cannabis is such a unique plant that can affect each person differently depending on strain, tolerance, THC content, and body chemistry, what’s too much for one person may be just enough for another. Therefore, the mantra “start low and go slow” stays true.

Anecdotally, as stated above, many of those who have experienced hangover symptoms report having used edibles or extracts. According to these conversations, the phenomenon seems to be far less common as a result of more traditional consumption methods such as smoking.


Who is Rick Simpson and what is Rick Simpson Oil (RSO)?

One could surmise that this is because it is much easier to overconsume with edibles than from smoking cannabis. With that in mind, some may find their symptoms are a result of waking up with a lingering high, due to the slow rate at which products such as edibles metabolize in the body.

Whatever the method of consumption, it may simply come down to a reduction in dosage to find a more even high that does not cause unpleasant lingering effects.

Does cannabis cause dehydration?

Many resources claim that cannabis directly causes dehydration and that this dehydration can lead directly to symptoms of a weed hangover. In fact, some even go so far as to make wildly exaggerated claims that cannabis is more dehydrating than alcohol. However, despite this seemingly “well-known” side effect, there is simply no science to back up the claim.


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Ultimately, what many people are mistaking for dehydration is actually dry mouth (aka cottonmouth), and the two are simply unrelated. Dry mouth, while terribly uncomfortable, is not a result of dehydration, but a lack of saliva.

So why does this happen? As studies show, the cannabinoid THC binds itself to the glands in the mouth responsible for producing the majority of saliva (these are known as the submandibular glands). In doing so, this binding temporarily halts the production of saliva, leading to the dry, uncomfortable sensation most of us have known at one time or another.

However, despite the fact that cannabis may not directly lead to dehydration, it’s worth noting the importance of staying hydrated while smoking—as well as in general. Studies seem to suggest that a large percentage of Americans are dehydrated and not consuming enough water during the day. Dehydration can lead to a slew of issues, including ones that medical cannabis may not be able to fully treat without the assistance of hydration.


What Are the Side Effects of High-THC Cannabis?

For example, an article from May 2016 details the importance of staying hydrated even when treating chronic back pain with cannabis. The author, a medical cannabis user, was perplexed that although the cannabis helped bring him much longer-lasting relief than the prescription medications he had tried, he was still experiencing severe back and spinal pain from time to time. After paying closer attention to his symptoms, he discovered the culprit: dehydration! Upon correcting his water intake, the author found himself feeling healthier with greater spinal flexibility.

Although there is no evidence to correlate cannabis directly with dehydration, many of the symptoms of a cannabis hangover may be improved by larger consumption of water, and generally speaking, it is good practice to make sure you’re staying hydrated.


Does Cannabis Make You Grumpy?

Cannabis hangover symptoms

Reported symptoms of a weed hangover include brain fog, headache, fatigue, nausea, and dry eyes. Since the aforementioned studies did not research all of these symptoms, much of what we know is based off user reports. It is possible, therefore, that other factors may come into play, and without proper studies we have no way to validate these claims with certainty. That said, there is enough commonality in anecdotal reports on this topic to warrant an honest conversation on the symptoms users are experiencing.


A Guide to Cannabis Allergies and Symptoms

Brain fog and fatigue

If you’ve ever woken up feeling groggy, unfocused, and in a daze, you’re familiar with brain fog. This symptom can make it very difficult to kickstart the day. Brain fog is incredibly unpleasant and may seem hard to snap out of, but there are some things you can do to help re-spark your battery, so to speak.

  • Get moving. Staring at a screen all day is not going to help. Try to start your day with a brisk walk.
  • Take a cool shower. The refreshing water should wake up your senses.
  • Adjust your eating habits. Make sure you eat healthy food and stay hydrated throughout the day to nourish your body.
  • Try a stimulant. For those who need an extra boost, a stimulant such as caffeine can give a foggy brain the jumpstart it needs.

How Does Cannabis Consumption Affect the Brain?

It may not completely resolve the feeling of sluggishness, but these remedies should help get you through the day more comfortably.


Another commonly reported symptom of the weed hangover is headache. Many attribute it to dehydration, but again, there’s no evidence to support the theory that cannabis directly causes dehydration. That said, it’s possible that when consuming cannabis in large quantities, one may forget to keep hydration in mind and as a result, end up not consuming enough water in the evening before bed.


Cannabis and sleep: 9 things to know about your herbal nightcap

Whatever the cause, if you wake up with a headache, it’s best to go the normal route in treating it:

  • Cold compresses
  • Temple massages
  • Over-the-counter medication such as aspirin, ibuprofen, or acetaminophen (make sure to follow dosing instructions)


Some consumers have reported experiencing nausea during a weed hangover. This seems to be less common, but can be terribly unpleasant nonetheless. If you wake up feeling nauseous, try to take it easy while you ride the feeling out. In more severe cases, make sure you are staying hydrated and try to eat some gentle, mild foods or opt for anti-nausea medication after checking with your physician.


What Is Cannabinoid Hyperemesis Syndrome?

Dry eyes

THC causes dilation in ocular capillaries, leading to the signature “red eyes” look as the flow of blood to the eyes increases. For most consumers, this clears up fairly quickly after smoking. However, if you wake up the next day and find you still have dry eyes, consider some rewetting drops to soothe the redness and restore moisture.


Why Smoking Cannabis Causes Red, Bloodshot Eyes

The “weed hangover” may remain a topic of contention for some, but until the experience can be studied more extensively to truly understand the causes and effects of this phenomenon, the best we can do is pay close attention to proper dosage.

Rae Lland's Bio Image

Rae Lland

Rae Lland is a freelance writer, journalist, and former editor for Weedist and The Leaf Online. With a focus on culture, music, health, and wellness, in addition to her work for Leafly, she has also been featured in numerous online cannabis publications as well as print editions of Cannabis Now Magazine. Follow her on Instagram @rae.lland

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  • The Resistance

    Great topic. This is a challenge for me since I prefer edibles for their effect and discreteness. But a late night edible is tricky if you also want to get some sleep. Sublingual absorption of mints helps a bit but not completely with hangover symptoms.

    Does anyone have experience comparing their typical THC intake with THC-CBD combination on hangover symptoms? This will be my next experiment.

    • Rosie May

      Have a look at my above post, it may help you shake the hangovers?

  • Open Minds

    THC doesn’t give you a hangover. However, when you smoke (combust) cannabis, the process of combustion creates harmful substances like benzene, carbon monoxide, naphthalene, toluene and polycyclic aromatic hydrocarbons (commonly known as PAHs). It’s these substances which are responsible for the hangover. If you vaporize cannabis, it decreases these unwanted substances by around 90%. I used to smoke and I would get hangovers but ever since I switched to a vaporizer, no more hangovers.
    As to edibles and extracts, it’s well known that these products have higher concentrations of pesticides in unregulated markets. Maybe this is the source of the hangover (besides the reasons mentioned in the article).

    • lovingc

      What is your source for these chemicals in the combustion of cannabis?

    • mmKay

      Animal studies show that weed does cause hangover when coupled with CB1 receptor antagonists. Since THC is fat soluble, in humans, you often don’t see typical (alcohol like) symptoms because there’s enough that stays in the fat to time release through the following days and binds to the CB1 receptors and titrates the user off THC gradually which staves off classic hangover symptoms (hair of the dog–style). But if you block the receptors so that the THC can’t bind, you see classic withdrawal symptoms in animals. It’s reasonable to think that this translates to humans as well and some individuals show severe hangover (maybe if their body fat is low) while others are more tolerant. Alcohol is the same way.

      • Rosie May

        Cell hydration improves after its membrane becomes more porous from the THC effect, a bit like other food oils we eat? Essential oils used occasionally work like it. The extra Hydrogen ions from the hydration(H2O) allow better glycolysis, the antioxidant/oxydisation hypothesis has flaws and is one of the many modern fallacies, like infection, vaccines, 911 collapse, most terrestrial TV, you get the idea.

    • Jenny

      Thank you Open Minds, your comment is very helpful. Which vaporizer would you use to smoke weed? I am not familar with this. Also, it sucks to hear about edibles because I thought maybe edibles would help me since I get so dehydrated smoking, but apparently not.

      • Open Minds

        Storz & Bickel. Expensive but they are the best.

        • Jenny

          Thank you so much.

        • I have a Plenty and a Volcano, and I prefer the Arizer vapes and the Herbalaire vapes, so I would definitely argue that Storz & Bickel are not “the best.” Some may prefer them, and they are in the top tier.

    • Lex

      Have you ever used a PAX? Because I thought it was considered a vaporizer, but I actually get the worst “weed hangover” symptoms when I smoke from that. After my high is gone I get such a bad brain fog that it makes it hard to do anything for the rest of the day but take a nap.

      • Open Minds

        The problem with PAX is temperature control. Once you go past 390F, you start vaporizing unwanted substances like benzene etc. Never vaporize past 390F. I use Storz & Bickel The Plenty which has very accurate temperature controls. I used to get that same day brain fog feeling and next day hangover when I smoked but stopped having that problem when I started using The Plenty.

        • Lex

          Thanks so much for the reply! I wondered if temperature could have been the culprit… it sometimes felt like it really was more like smoke. I will have to try a better vaporizer!

          • P.J. Rafter

            It’s maybe worth remembering that THCv is a much higher-boiling substance than THC or CBD and so with a low-T vape the soaring magic of AG could be essentially lost…

          • Lex

            AG? What is that?

          • Susie Mmpatient

            It’s a metabolite of THCV, which latter is a (usually) minor cannabinoid that supposedly decreases the appetite (no munchies!), may lower blood sugar, and gives an alert, focused if somewhat racy and short-lived high. Not sure what magical properties P.J. thinks the AG has. I’m dubious about THCV myself, having not tried (because it’s impossible to find) the one strain bred just to be high in THCV, Doug’s Varin. Durban Poison is supposed to be particularly high in it, yet gives me the munchies like crazy. Willie Nelson is another good source, and that did not in fact give me the munchies, but try finding it, either.

          • Rosie May

            Yeah the high heat cracks the carbon, makes a strong molecule that isn’t organic parse.

      • P.J. Rafter

        I’ve found, over the years, that whether you get a hangover depends on the constituents of the chemotype you’re smoking…

        You’ll actually feel refreshed after a night of, say, pure Colombian or Thai buds.

      • Rosie May

        It probably makes the cells porous(allows release of toxins), think infrared energy,heat, that has the same effect, biologically).
        I don’t take synthetic man made drugs that the liver chemistry can’t recognise!

      • Yeah, they sell Pax as a vape, and that’s nonsense. My experience is that it burns the substance.

    • telefishopolis

      Utter nonsense. If this were true, cigarette smokers would be in a perpetual state of hangover.

      • Susie Mmpatient

        If they quit smoking, they ARE in a perpetual state of hangover. Of course that’s quite possibly the sudden absence of the stimulant nicotine. Woe, homeostasis.

    • Rosie May

      No, it’s all superstitious conjecture imho.

    • No.

      I’m reading this because I just experienced one after vaping too much. This was my own organically grown, and I vape at 165ºF, so I’m not combusting. It rarely happens, but it does occasionally happen. As the article says, it’s usually edibles. This also doesn’t imply that combustion causes it.

  • Jenny

    I was reading this hoping that you all would mention dehydration and I was excited when I saw it, then you said it’s not possible. I’m here to tell you it is! Smoking weed does dehydrate and when I smoke too much, I wake up with my neck and back hurting so badly, I can’t function or move the whole day. No matter how much water I drink, it DOES happen. I have to chill on smoking it for a few days until I return back to nomral. I don’t smoke ciggs or drink.

    • Yaspar

      Have you tried a sativa variety?You may find you wake up refreshed and eager to start the day.

      • Susie Mmpatient

        Yes, but it’s hard to find sativas that are effective (many are counterproductive) if what you’re trying to treat is insomnia, anxiety and pain.
        Nonetheless, I had such a bad weed hangover this morning — brain fog, dizziness, headache, sluggishness, nausea and lethargy — off a few vape hits of Night Nurse mixed with OG Kush last night, that I may have to go on a desperate hunt for my beloved ACDC. Moving from LA to Chicago as a medical user has been a major bummer. They only just dropped the requirement that one has to be fingerprinted and have a criminal background check (among many other requirements) to get a med card here. (Fingerprinted and be subject to a background check? Seriously? Can you imagine if they required you to be fingerprinted and background-checked to buy alcohol or cigarettes?) Chronic pain isn’t even a qualifying condition; nor are anxiety or insomnia or nausea. And there seem to be about 17 dispos, compared to 1,300 (a while ago; I’m sure there are more now) in the greater LA area. There’s like a 10-week wait to get your med card after you supply all the paperwork (plus your passport-type photo and the check for $100 for a year’s card), because all applications go through one state office. It’s a great city, but I can only hope that a change of governor and the massive state fiscal crisis push it and the rest of IL on into the world of recreational legality. What politicians won’t do for public health, they are often very happy to do for money.
        And now I see that weed hangover seems to involve a certain grouchiness as well. 🙂
        Any suggestions for sativas that won’t keep you awake whe you’re trying to go to sleep, or that slow your brain down rather than speed it up?

        • Rosie May

          Cadmium your trouble bruv, I see it all the time.

    • Rosie May

      Neck would be a zinc deficiency, back is carotene and molybdenum, only quarter dose any supplement unless under supervision! Better late than not at all.

    • Did you actually scientifically check your level of hydration? I somehow doubt it.

  • P.J. Rafter

    I’ve never once had a hangover from Indica-free sativa buds ─ what you feel next day is more the opposite of a hangover…

    • Yaspar

      Same here! I try to avoid indicas, as they give me a poor-quality high, and a groggy foggy hangover that persists the entire next day. Sadly, indicas seem to have taken over the scene, and sativas are hard to find, at least where I live.

    • Rosie May

      Moderation is the key.

  • QRAngela

    I use concentrates only, in the form of shatter, and I get headaches quite often. I can promise you it had nothing to do with low body weight, dehydration, or combustion, but I do believe it has something to do with my breathing. After I vape shatter my breath gets shallow and I believe I breathe shallow all night. I find I wake up more during the night if I vape later in the evening. Now this evening I vaped shatter earlier and fell asleep in my chair for two hours and woke up with a pretty bad headache also. Its enough to send me back to the dry herb, even though I like the lasting power of shatter. A little goes a long way.

    • Rosie May

      That will be the heavy metals metabolising, trust.

  • Yaspar

    There seems to be considerable personal variation in the cannabis hangover. While I am extremely prone to indica hangover, sativas wake me up with a smile. Friends of mine have no hangovers, regardless of variety. They think I’m a bit obsessive about my choices in cannabis, but I really can tell the difference, within minutes of smoking, and definitely the next morning!

  • Rosie May

    Smoking is a fair source of oils delivering minerals, you feel better getting them, but what are you getting? Organic plants, grown with organic food? We all built up a tissue level of industrial waste minerals, called heavy metals, we do. Certain activities allow our body cells to become more porous to the transport of these heavy metals.
    One of these is Cadmium, it binds like zinc to proteins and doesn’t leave the body until a bacteria call PLANTARUM encapsulates the waste and takes it to the bowls for excretion. I’m not talking chelation therapy either. Cadmium, it’s worse than radiation I think, 32 year half life, bla, bla, bla.
    Once it’s gone the cells either die, or recover their glycolysis and start to crave Vitamins. It’s common to see prominent vit deficiency symptoms at this stage. Methylated B bits are best. 100-200mcg now and then of chelated Molybdenium is essential for all. A small pinch of Boron in good water once a week allows brain plasticity through the activation of the Calcium hormone and a host of other essential things. No more that 200mg of natural source vit C at a time. A swig of virgin olive oil now and then for Tocopherols, no more as all veg oils are poisonous! All this reverses brain fog, but be aware, Cadmium drives the ego, the artificial excitement the extreme laziness, secretive, rage, haste, confusion, the shakes(Parkinson?), migraine(some hangovers?!), kidney stones, macular degeneration(eye), hearing loss, grey hair, balding, brittle bone, all scar tissue, I won’t put ‘etc’ to end that list because I don’t want to cause unnecessary worry for anyone reading this. The list is made from my own personal experiences along with studies, I’m not a repeater. It’s ALL reversible for everyone, it is.
    If it burns your throat, it’s not the hot temperature(that would burn your mouth), it’s the Cadmium in the plant.
    How much Cadmium does your ego want?
    Sources of Cadmium I have located are: instant coffee, normal cigarette papers, car brake dust, poor soil, bean lectins, some ash. For hundreds of years heavy metals are known for their psychological effect on civilisation, do you want to be killed slowly?
    I’m not frank, this ain’t Rosie, we all have industrial waste effects. It’s real, not a prank, wakey wakee. Are you outside the ego box or still captured by all the false drama? You can find out in a few days with Plantarum, it will ground you out man…

  • Kevin McCoy


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