Q: Are headstands safe?
A: Not always. Aside from the risk of neck injury, headstands can cause spikes in intraocular pressure (IOP), the pressure of fluid in the eye. For instance, an Indian study in the journal Ophthalmology back in 2006 found that when yoga practitioners did headstands, their IOP temporarily doubled, on average. And a small study in PLOS ONE in 2015 found that common head-down yoga poses (such as the downward-facing dog) increase IOP in people with or without glaucoma.
While brief spikes in IOP are nothing to worry about in healthy eyes, there is concern that they can, over time, progressively damage eye tissue and promote or worsen glaucoma and some other eye conditions. Thus, anyone with glaucoma (or just elevated IOP) should avoid head-down poses. Older people and anyone at risk for glaucoma should get a full eye exam before doing them.
Some people have heartburn after doing headstands. There are no studies to confirm this, but the position could aggravate heartburn by allowing stomach acids to back up into the esophagus. People who tend to get heartburn should not even lie down after meals, let alone do headstands.
This article first appeared in the UC Berkeley Wellness Letter.
Also see If You Do Yoga, Be Careful!