Why The Red Eyes?


For generations, the red-eye has been a tell for mothers and bosses all over the world. It is the main tell that someone has been smoking weed. There surely isn’t one single stoner in the world who hasn’t wondered why smoking herb causes itchy, red, dry eyes. Aside from keeping the eyedrop companies in business, what is the reason for this phenomena?

It seems that THC is behind the red-eye. THC in the system can also cause a dry mouth (aka cotton-mouth) and/or a drop in blood pressure. The lower blood pressure is actually what has an effect on the color of the eyes. When your blood pressure decreases, the capillaries and blood vessels dilate. When ocular capillaries dilate, the flow of blood to the eye is increased and reduces intraocular pressure. With the dilation of the ocular capillaries, more blood flows to the eyes, causing red, veiny eyes that screams, “I’m high!”. While the increased blood flow does create redness, it also helps decrease ocular pressure which is beneficial for glaucoma patients.


Since THC seems to play a role in red-eye, it’s possible that smoking cannabis flowers with lower THC helps to reduce the problem. This information also means that it doesn’t matter how we get high – – edibles, vapes, blunts, or bong rips- we will generally always have red eyes as long as there’s THC in play.

So there we have it, THC is the culprit for the red-eyed Jedis. Which means, as long as we’re getting high and trying to stay incognito, we’ll need those handy eye drops.

February 2, 2018

by Cara Wietstock

Profile photo of Cara Wietstock
Cara began working in the retail cannabis industry of San Francisco, CA in 2011 and continued in that sector for years. In 2015 she put down her budtender hat and dedicated herself to writing full-time. Her passion for the written word and deep respect for the healing properties of the cannabis plant fuel the passion in her posts.


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