It's a fact that as you age, the hair on your head, eyebrows, and especially your eyelashes start to thin. Because most of us want long, thick, full eyelashes, we are willing to invest in eyelash extensions, falsies, volumizing mascaras, and even lash-boosting supplements to get a mile-long fringe. One of the most underrated ways to get better-looking lashes is with castor oil. It's long been used for its lash-boosting abilities, making castor oil for eyelash growth a go-to treatment. But using it on the eyelashes works differently than eyelash serums, so there's plenty to unpack if you want to give it a shot. We tapped two dermatologists and a trichologist for their expert insight and the truth about using castor oil for eyelash growth.

Meet the expert

What Is Castor Oil?

Castor oil is derived from castor beans from the Ricinus communis plant. It has a long skincare history dating back to ancient Egypt and India for its numerous health, beauty, and skin benefits. As Dr. Garshick explains, the Ricinus communis plant is rich in protein, antioxidants, nutrients, and fatty acids, which makes castor oil beneficial for moisturizing the skin, scalp, and hair.

Benefits of Castor Oil for Eyelash Growth

Even though there's a lot of chatter surrounding castor oil and its ability to grow longer, stronger, thicker lashes, truth be told, the oil itself can't physically grow better eyelashes. But castor oil can help strengthen the eyelashes and make them appear thicker. According to Brown, castor oil contains 90 percent ricinoleic acid, which is high in triglycerides to help moisturize and strengthen the eyelashes. "Castor oil also contains omega-6 fatty acids, which may help improve hair health." While no studies prove that emollient-rich castor oil helps eyelashes to grow, Dr. Brown says using the oil on the lashes can help them appear fuller. "A study reported that castor oil helps the "luster" of hair, which may be why it helps the eyelashes to look fuller. Other research found that ricinoleic acid may act as a prostaglandin D2 inhibitor, indicating that it may help prevent hair loss."

Friese adds that the naturally hydrating nature of castor oil can help create a healthy environment for eyelash growth. Still, using castor oil regularly on the eyelashes nurtures the hair, which Dr. Garshick shares will leave them stronger and healthier. "Anecdotally, people have noticed improvement in their lashes because castor oil has antimicrobial and anti-fungal properties," she adds. Nonetheless, applying castor oil to the eyelashes can improve their current state, potentially preventing the delicate eyelash hairs from breaking. 

How to Use Castor Oil on Your Eyelashes

There are two ways to use castor oil to help grow eyelashes: applying straight organic castor oil directly to the eyelashes or using a product containing the oil as a key ingredient. Friese prefers straight castor oil because "you know exactly what ingredients you are using."

For castor oil newbies, Dr. Brown recommends always performing a patch test first by applying a small amount of oil to the upper arm's inside and covering it with a bandage for a few days. If redness or irritation develops under the bandage, the patient likely has an allergy to it. "Even though castor oil is present in many cosmetics and skincare products and is considered generally safe, some patients may develop an allergy to it over time."

Castor Oil-Based Eyelash Products

If you choose the do-it-yourself route, use a high-quality cold-pressed organic castor oil that isn't expired. Friese recommends putting the oil onto a Q-tip or a clean, fresh mascara or spoolie brush and then applying it to clean eyelash hairs free of makeup. "Glide the Q-tip or brush along the upper and lower lash lines, and coat each lash with the oil. Do this before bed to give the oil enough time to penetrate the lashes."

Be careful not to have too heavy of a hand and overload the hairs or surrounding skin with oil since too much of it can potentially clog the surrounding pores, leading to clogged pores or milia. Come morning, wash your face well and remove any residue from the eyelashes and eye area with micellar water.

For most people, castor oil is a safe and natural alternative to synthetic ingredients used to grow eyelashes. Of course, there are a few instances where you'll want to avoid using castor oil altogether, like if your skin is inherently sensitive or you are prone to developing styes in your eyes. It's also best to bypass using castor oil on your eyelashes if your eyes or the surrounding skin are irritated or infected or you have a history of contact allergies or allergic reactions.

Frequently Asked Questions

• How long does it take to see the benefits of castor oil on the lashes?

  You may see some of the initial benefits of castor oil as early as four weeks. However, Dr. Garshick says it generally takes two to three months to see improvement. Sticking to a consistent routine is key.
  

• How does castor oil compare to eyelash growth serums?

  Castor oil and eyelash growth serums work differently and aren't an apples-to-apples comparison. "Latisse is the only FDA-approved eyelash growth serum. It contains bimatoprost, a prostaglandin analogue, which works to help new hair growth by increasing the amount of time hair is in the anagen phase," Dr. Brown explains. "Castor oil does not do this, so it isn't likely to grow new hair, but it will make the hair healthier and appear fuller."
  

• Can castor oil be used by those with eyelash extensions?

  Oil of any kind is known to break down the glue that adheres eyelash extensions to the eyelashes, so to be safe, it's probably best not to use castor oil on eyelash extensions. However, if you're taking a break from eyelash extensions, it's a good time to try castor oil for eyelash growth.