The HERB Blog

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How Cannabis Causes 'Red Eye'


"I've got allergies," is a statement that only goes so far when it comes to red eyes! And though it may be valid most of the time, red eyes imply that perhaps you are high. Of course, eye drops can remedy the situation...most of the time.

We decided to take a moment and review why our eyes get bloodshot when we ingest cannabis and the lovely active ingredient of THC.
Leafly reports, "The primary cause for reddening of the eyes after smoking cannabis also happens to be the main reason that the plant is famous as a treatment for glaucoma. In short, THC lowers blood pressure, which in turn causes blood vessels and capillaries to dilate. The ocular capillaries dilate, which increases the flow of blood to the eyes and reduces intraocular pressure. Increased blood flow creates the redness, while the decrease in pressure is the same effect that benefits glaucoma patients."
It's also dependent on how much THC you are consuming. Say you smoke some flower with a lesser amount of THC per dose. In this instance, your eyes might not get as red, but once you start ingesting a higher dose of THC, whether it's a couple packs of 100 mg gummies, or a high THC strain like this Lava Cake (testing out at approximately 30% THC)--hello red eyes!
Allergies DO tie in with interaction of combustion of cannabis, aka smoking a joint. Essentially if the consumer is easily irritated by smoke, whether it's cannabis, tobacco or sage smudging--their eyes will probably become irritated and red. This can be avoided by ingesting edibles or vaping cannabis oil.
While red eyes can just be a side effect from intended beneficial effects for glaucoma and intraocular pressure, you can still gain those benefits and relieve your red eyes. Here are some tips from Leafly:
There are a few simple steps one can take to minimize or reduce redness of eyes during or after smoking:
- Opt for low or no THC strains. Strains high in CBD and the like may be a desirable alternative for those looking to lessen red eyes when toking.
- Have eye drops on hand, especially brands specially formulated to reduce eye redness.
- Stay hydrated by drinking plenty of water. Increasing your fluid intake may help alleviate the dryness you experience.
- Simply let it run its course and plan smoke sessions for leisurely moments spent at home.
- Ultimately, red eyes are not harmful and come with no negative outcomes (other than the dated stigma associated with them).
The next time you're a bit concerned about red eyes, follow these tips--or just bring your sunglasses!
Information referenced from Leafly.