Did you know that castor oil is an (inactive) ingredient in many over-the-counter eye drops? It’s also used as a base for several prescription medications used for treating dry-eye. Various people have claimed that castor oil can heal other eye issues, from under-eye bags and eyelash loss to floaters and cataracts. Here, optometrist Dr. Joseph Allen discusses what he’s learned from diving into research concerning castor oil and its effects on eye health.*

Castor Oil for Dry-Eye

Castor oil relieves dry-eye, Allen explains, by preventing the eye’s natural tear film from evaporating. It also provides additional lubrication for the top eyelid as it glides over the eyeball.

In one study that he references, eye drops containing castor oil were administered twice daily for six weeks. At the end of the six weeks, the majority of participants had relief from dry-eye, as well as more stable tear film.

He advises against buying regular castor oil from the store and putting it directly in your eyes, as there are safety concerns, among them:

• 100% castor oil is very thick, and does not mix well with tear film; it leaves “ropy” strands on the eyeball, causing blurry vision. The formulations used in research studies contain castor oil diluted to about 2%.
• Castor oil has been found to be cytotoxic to the human conjunctiva cells, which make up the membrane covering the white part of the eye. Undiluted castor oil can cause irritation and even damage, or kill, these cells.
• Proper storage is also an issue. Too-warm storage conditions can lower castor oil’s acidity, leading to greater irritation of the eye.

Lastly, castor oil from the store is not regulated, the way medications are. Because of this, Allen says, “There’s no way to know exactly what’s in it, and it’s usually not sterile.”

Benefits of Pure Castor Oil

Despite the dangers of putting 100% castor oil directly into your eye, Allen says that there do seem to be some benefits to using it on the outside of the eyelid and on the skin around the eye. For instance, in one study that Allen references, 100% cold-pressed castor oil applied twice a day for four weeks reduced blepharitis (inflammation of the eyelid).

In addition to reducing inflammation, castor oil has been shown to reduce:

• Spider veins,
• Loss of eyelashes,
• Eyelash crusting, and
• Friction of the upper eyelid when gliding over the eyeball.

Castor Oil for Eyelash Growth

While he couldn’t find any studies that specifically focused on the use of castor oil for eyelash growth, he does say that castor oil has a similar chemical structure to prostaglandins, which have been shown to support hair growth, including eyelashes.

Prostaglandins are a group of lipids (fats) that act like hormones, and are found in almost all body tissues. Eye drops containing prostaglandin analogs (PGAs) have been used to treat glaucoma since 1996, and the American Academy of Ophthalmology lists “an increase in thickness, number and length of eyelashes” as a potential side effect of PGAs.

Castor Oil for Eye Floaters and Cataracts

As with eyelash growth, Allen was unable to find any studies that directly explored the effects of castor oil on either eye floaters or cataracts. Based on his own knowledge as an optometrist, however, he thinks it unlikely that castor oil by itself would be able to penetrate the layers of the cornea, conjunctiva, and sclera to be absorbed into the deeper ocular tissues where floaters and cataracts form.

*Allen, J. [Doctor Eye Health]. (2024, March 6). Castor Oil for Your Eyes: Dry Eyes, Eye Bags, Eye Floaters, and Cataracts [Video File]. https://www.youtube.com/watch?v=RuvyCYpVOvM