why does weed give me a headache

Why Does Your Head Hurt After You Smoke Weed?

We’ve likely all heard of some of the side effects that are possible when smoking marijuana. What is less talked about, however, are some of the milder symptoms that occur from periodic cannabis consumption.

While there is minimal evidence currently available on the matter, many cannabis users report headaches after smoking weed. Is it possible for the two to be connected in a physiological sense?

In this article, we take a look at the facts in order to try and answer this question. Can cannabis cause headaches, or are other factors at play? Here is all you need to know and more.

The Weed Hangover

If you have ever smoked a little more than you should have, you will probably understand exactly what we mean by the term ‘weed hangover.’ For those who are less in the know, let us explain.

Most of us have been there; a quiet night in with a few drinks turns into an over-indulgent party full of fun and far too much alcohol. You wake up the next day feeling miserable, with a terrible headache after smoking weed and an intense nausea from the alcohol.

Sound familiar? Well, there are many cannabis users out there that claim marijuana can do the same thing in terms of resulting in a wicked headache.

While not scientifically proven, many marijuana enthusiasts report telltale symptoms of a hangover the day after a heavy smoking session. And yes – along with things like fatigue, dry eyes, brain fog, and nausea, severe headaches are a common side effect that one might experience after heavy use.

In a general sense, we now know from years of research that cannabis is a non-toxic plant. Unlike alcohol, which can be extremely dangerous (and even lethal in high doses), there has never been a reported case of overdose or death by consuming cannabis.

Thus, even if these mythical weed hangovers were a real physiological thing, they would not compare in intensity to the hangover that results from drinking too much alcohol. Furthermore, even if we could objectively define the symptoms that result from a weed hangover, the effects would likely be greatly diluted in comparison to the physiological effects that excess alcohol has on the body.

But, is it possible that weed does, in fact, cause a migraine? Or, to a less severe extent, does it make physiological sense to get a headache after weed? Let’s dig a little deeper.

Weed Headaches: The Myth Behind Cannabis and Dehydration

It’s well-known that one of the critical causes of headaches is dehydration. But is dehydration a result of cannabis?

The evidence on cannabis usage and dehydration is inconclusive and warrants further study. Many people attribute dry mouth, or ‘cotton mouth’ to dehydration, but this is inaccurate. Studies have shown that actually, cottonmouth has to do with lack of saliva and the way that cannabis interacts with the body – namely the CB1 and CB2 receptors of the endocannabinoid system.

With that in mind, what else is there to explore when it comes to marijuana and headaches (informally known as a weed headache)?

The Facts About Cannabis and Headaches

Among the misinformed claims that cannabis can bring about a killer headache, are the many studies done on marijuana as an effective treatment for headaches and migraines.

A study published as recently as 2016 showed that across 121 adult migraine sufferers, the occurrence of migraines was more than halved after the consumption of cannabis. In another study from 2017, authors observed that patients reported fewer migraines per month after cannabis use.

Here are some of the published statistics from the studies:

  • The average number of migraines reduced from 10.4 per month to 4.6
  • Approximately 85% of the participants reported having fewer migraines per month using marijuana
  • Only 12% of the 121 participants stated they saw no change in the frequency of their migraines

Researchers from the 2016 publication in Pharmacotherapy (see link above) remarked that “most patients used more than one form of marijuana, and used it daily for [the] prevention of migraine headache.” They also concluded that “inhaled forms of marijuana were commonly used for acute migraine treatment, and were reported to abort migraine headache.”

What Can You Do to Combat a Headache Caused by Weed?

While there is no evidence for the argument that cannabis itself brings about headaches, it is possible that other factors related to smoking marijuana can contribute. Whether you are out in the sunshine enjoying cannabis with your friends or having a heavy smoking session inside, there are a few aspects to consider if you suffer from “after weed” headaches.

If you are going to be smoking outside enjoying the summer, remember to drink plenty of water before, during, and after smoking. While there may not be evidence of cannabis causing headaches, there is plenty of scientific evidence for the sun causing dehydration, which we know brings on headaches. Keeping on top of your fluid intake and giving yourself breaks in the shade should help to combat those pesky brain pains.

The same rule is applicable if you are getting high indoors, as it can be so easy to forget to drink! Keeping water next to you will serve as a visual reminder for those occasions where you are too intoxicated to otherwise remember to hydrate.

There are of course a few other tips and tricks, such as avoiding salty foods (which may be easier said than done once the munchies kick in!), and ensuring that you don’t overdo it.

In any case, it should be fairly clear by now that cannabis itself is not the main reason for those ‘weed hangover’ symptoms – headaches included.

Final Thoughts on Marijuana and Headaches

To summarize, the answer to the question of “why does my head hurt when I smoke weed” doesn’t necessarily involve cannabis. Headaches can occur as the result of a number of different things, but too much cannabis is not likely one of them.

Using common sense when enjoying marijuana will usually be enough to see off any headaches. Perhaps a particular strain doesn’t agree with you, or maybe you simply haven’t had enough to drink that day.

What we do know is that marijuana does not cause dehydration. Furthermore, it is not conclusive that a headache after weed is caused by the cannabis itself. So for those who are concerned about headaches after smoking a joint, perhaps consider what other factors might be at play!

Why does your head hurt when you smoke marijuana? Isn't weed supposed to help you get rid of headaches – not cause them? Let's bust this conundrum.

Does weed give you a headache?

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  1. Evidence that cannabis helps with headaches
  2. How might cannabis work on the body to ease headaches?
  3. Evidence that cannabis can exacerbate headaches
  4. Bottom line

One of the curiosities of cannabis is that it can lead to a range of responses in users. When it comes to headaches, some find that it alleviates pain, while others claim it exacerbates it. Anecdotes abound identifying cannabis as the culprit for kickstarting throbbing head pain. On the other hand, individuals who regularly experience headaches and migraines swear by weed to reduce the severity or frequency of their episodes.

When it comes to headaches, some find that it alleviates pain, while others claim it exacerbates it. Photo by: Gina Coleman/Weedmaps

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While individual and anecdotal experience is always valid, diving into scholarly research can offer a more expansive view of what’s going on.

So, what does the research say about cannabis and headaches?

Evidence that cannabis helps with headaches

Evidence has been mounting over recent years indicating the utility of cannabis as a treatment for headaches. Conventional analgesics used to manage headache pain are not always effective. What’s more, they can sometimes lead to more headaches — a condition known as medication overuse headaches.

A number of studies and surveys of human participants have presented findings indicating that cannabis may ease headache and migraine severity.

A July 2020 study published in the Journal of Integrative Medicine explored the efficacy of dried cannabis flower as a treatment for headache and migraine pain. Between 2016 and 2019, 699 participants engaged in the research, sharing details about the intensity of their symptoms and the dried cannabis flower they used to treat their pain. Changes in pain intensity were measured on a 0-10 scale both before and after consuming cannabis.

The authors found that 94% of participants experienced symptom relief within a two-hour period. The average reduction of symptoms was 3.3 points on a ten-point scale, with males experiencing greater relief than female users. Young users also experienced more significant relief than older users. Cannabis containing THC levels of 10% or higher appeared to offer more effective symptom relief for headache sufferers.

A June 2020 study published in the Journal of Pain investigated the effects of cannabis on headaches and migraines. The study used archival data from Strainprint, a medical cannabis app that enables patients to track symptoms before and after using cannabis. The study’s authors analyzed data from 12,293 sessions where cannabis was used to treat headaches, and 7,441 sessions where it was used for migraines.

Cannabis reduced the symptoms in 89.9% of the headaches and 88.1% of the migraines. Similar to the study published in the Journal of Integrative Medicine, men were slightly more likely to experience a reduction in headache pain than women (90.9% vs 89.1%). Users reported a 47.3% decrease in headache severity and a 49.6% decrease in migraine severity. The study’s authors found that neither cannabis strain nor cannabinoid concentration appeared to impact on therapeutic efficacy. While repeated cannabis use sometimes led to developing tolerance to its effects, cannabis didn’t appear to lead to medication overuse headaches associated with conventional treatments.

For Rosemary Mazanet, M.D., Ph.D., and Chief Scientific Officer of Columbia Care, there is a general consensus among experts that cannabis may relieve pain. “There is evidence that migraine headaches may respond particularly well to cannabis, and the underlying endocannabinoid system may be involved in migraine headaches,” explains Mazanet. “And cannabis is known to help with nausea in general, which can accompany migraines.”

How might cannabis work on the body to ease headaches?

The body’s serotonin system is a critical player in headaches and migraines. Low or fluctuating levels of serotonin are associated with headaches and migraines. Serotonin is also implicated in the body’s endocannabinoid system. Anandamide, one of the two main endocannabinoids found in the body, potentiates serotonergic receptors. Low levels of anandamide can also cause headaches and migraines. In fact, researchers theorize that migraine is one of several symptoms caused by Clinical Endocannabinoid Deficiency syndrome.

Cannabinoids demonstrate dopamine blocking and anti-inflammatory properties that may also be relevant in treating migraines. Photo by: Gina Coleman/Weedmaps

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Evidence suggests that the dysregulation of the endocannabinoid system may result in headaches and migraines. Individuals who are deficient in anandamide may therefore benefit from cannabis medicine, as the cannabinoids in cannabis can mimic the body’s endocannabinoids. Cannabinoids also demonstrate dopamine blocking and anti-inflammatory properties that may also be relevant in treating migraines.

However, other factors, such as stress or lack of sleep, can also contribute to headaches. In these cases, the efficacy of cannabis may rest in its ability to ease stress and induce sleep.

Preclinical research has helped us to understand one of the mechanisms that enable cannabis to provide migraine relief. The CB1 receptor is a therapeutic target for migraine. Delta-9 THC activates the CB1 receptor, reducing migraine-like pain when delivered at the appropriate dose and time. THC is critical to achieving this efficacy, because it has a high binding affinity with the CB1 receptor. CBD, which has less of an affinity for the receptor, is unlikely to provide much relief if consumed without THC.

“THC in cannabis acts on receptors in the nervous system to alleviate pain and result in relaxation and calm,” explains Mazanet. “CBD use can also result in a reduction in inflammation over time. These effects combined can help people manage their stress and improve their sleep — because poor sleep is a known cause of headaches — and thus relieves their headache pain.”

Evidence that cannabis can exacerbate headaches

However, the waters become muddied by claims that cannabis can also trigger or exacerbate headaches. The 2020 Journal of Pain study also found that in 2.4% of headache cases and 3.1% of migraine cases, cannabis exacerbated headache symptoms.

The 2017 study published in the Harm Reduction Journal also found that cannabis can lead to worsening headache symptoms or even trigger episodes. The authors surmised that factors such as timing, frequency of use, administration method, and dosage might be influential. They also pointed out certain cannabinoids and terpenes may ease headache pain, while others might exhibit opposing effects.

Headaches have also been associated with “weed hangovers.” Excessive consumption of cannabis sometimes results in what’s colloquially known as a weed hangover the following day. Brain fog, groggy feelings, and headaches are commonly identified elements of the hangover.

Withdrawal after chronic cannabis use may also spur a headache. In a study of 469 frequent cannabis smokers published in Drug and Alcohol Dependence in 2010, 23.2% experienced headaches due to cannabis withdrawal.

According to Mazanet, sensitivity to certain cultivars may also incite headaches. “Some people are sensitive to THC strains that might cause them to experience anxiety, and that would not be a good thing for someone who had a headache to begin with,” says Mazanet. “People who know they are sensitive might want to try a hybrid product or one that contains CBD as well as THC.”

Bottom line

In general, the evidence points towards cannabis potentially being more helpful than harmful when it comes to headaches.

“There are many causes for headache, but the anxiety, muscle spasms, inflammation and other contributors to headache pain are usually reduced by cannabis, not provoked by it,” states Mazanet. That said, “deciding which cannabinoid to use for headaches is a very personal choice because people respond differently.”

As the studies show, there don’t seem to be any hard and fast rules about which cannabinoids or ratios work best for headaches. Experimenting cautiously and responsibly with different cannabis strains to temper headaches may be critical to unlocking what works best for the individual. Cannabis products and cultivars with a healthy quantity of CBD can also help to minimize undesirable side effects like anxiety.

While individual and anecdotal experience is always valid, diving into scholarly research can offer a more expansive view of what’s going on. So, what does the research say about cannabis and headaches?