Soybean Oil Eye Drops for Dry Eyes (Emustil)

Clinical author’s note (Michael Stewart, 11/03/2025): Emustil4 eye drops have been discontinued in the United Kingdom. At the time of review, there are no branded or generic products containing soybean oil available in the UK. Products may still be available in other countries. This medicine leaflet is based on medical information available in the UK at the time of writing and is left here for reference purposes. Please also refer to the manufacturer’s information supplied with your medicine.

Soybean oil eye drops act as artificial tears. They make dry eyes feel more comfortable. You can use the drops up to four times a day.

About soybean oil eye drops

Soybean oil eye drops, such as the discontinued Emustil4, are a type of eye lubricant designed to alleviate the discomfort associated with dry eyes in both adults and children. These drops function as artificial tears, providing essential moisture to the ocular surface.

Emustil4 eye drops contain two key ingredients: 7% soybean oil and 3% natural phospholipids derived from egg yolk. The soybean oil primarily relieves eye dryness and soreness by forming a protective lipid layer on the tear film. Natural phospholipids, which are naturally present in tears but often reduced in individuals with dry eyes, help stabilize and thicken this lipid layer.

These drops moisten, soothe, and lubricate the eye’s surface, enhancing comfort, particularly for those suffering from evaporative dry eye disease (DED), a condition involving multifactorial disruptions in tear film physiology. Clinical studies have demonstrated that oil-in-water emulsions like Emustil improve tear film stability, reduce evaporation rates, increase non-invasive tear break-up time (NITBUT), and enhance lipid layer thickness.

Emustil4 was available on prescription or over-the-counter through pharmacies in single-use, preservative-free units (typically 20 x 0.3 ml). It is particularly indicated for reducing tear evaporation and managing symptoms of Meibomian Gland Dysfunction (MGD). Research supports its use in both protection (pre-exposure) and relief (post-exposure) modalities under dry environmental conditions, such as low relative humidity (RH) environments (e.g., 5% RH).

In a controlled environmental chamber study, Emustil significantly mitigated tear film disruptions in healthy subjects exposed to ultra-dry conditions. Pre-exposure application was found to be more effective in preserving parameters like tear volume, NITBUT, and lipid layer thickness compared to post-exposure use. This makes it suitable for individuals working in arid settings, such as offices with dry air conditioning or high-altitude environments.

Additional evidence from peer-reviewed studies indicates that Emustil, as an anionic emulsion with natural phospholipids, improves tear volume, reduces corneal damage, and enhances subjective symptoms when used four times daily, either alone or combined with other agents like sodium hyaluronate. Compared to other emulsions (e.g., castor oil-based), it shows robust efficacy in stabilizing the tear film lipid layer.

How to use soybean oil eye drops

Proper administration is crucial for maximizing the benefits of soybean oil eye drops and minimizing contamination risks, especially since they are preservative-free.

• Wash your hands thoroughly with soap and water before handling the drops.
• Twist off the tip of a single-dose unit carefully.
• Tilt your head back slightly and use your index finger to gently pull down the lower eyelid, creating a small pocket.
• Hold the unit upside down close to the eye, ensuring the tip does not touch the eye or eyelashes to avoid contamination.
• Apply gentle pressure to release one drop into the pocket formed by the lower lid. Use a second drop only if the first misses the eye.
• Close the eye for 1-2 minutes and press lightly on the inner corner of the eye (near the nose) to prevent drainage into the tear duct.
• Repeat for the other eye if both are affected.
• Discard the single-use unit immediately after use; do not save for later.

A short instructional video from the manufacturer demonstrates this process, emphasizing the milky white emulsion’s easy application.

Getting the most from your treatment

To optimize relief from dry eyes, follow these evidence-based guidelines:

• Read the manufacturer’s printed information leaflet supplied with the pack for detailed instructions and potential side effects.
• Instill one drop into the affected eye(s) up to four times daily. Adhere strictly to your doctor’s prescribed regimen if applicable.
• If you miss a dose, apply it as soon as remembered; do not double up.
• Initial application may cause temporary blurred vision due to the oil emulsion; wait until vision clears before driving or operating machinery.
• When using multiple eye products, space applications by at least 10 minutes. Apply lubricants like Emustil last to prolong contact time with the ocular surface.
• Monitor symptoms; if no improvement within a few days, consult your doctor for further evaluation, as persistent dry eyes may indicate underlying issues like MGD or severe DED.

Clinical data supports frequent use (e.g., four times daily) for enhancing tear film parameters and reducing corneal staining.

Can soybean oil eye drops cause problems?

Soybean oil eye drops like Emustil are generally well-tolerated and unlikely to cause side effects. The preservative-free formulation minimizes irritation risks.

Common transient effects include mild blurred vision upon instillation, which resolves quickly. Rare allergic reactions to soybean oil or egg-derived phospholipids may occur; discontinue use and seek medical advice if severe irritation, redness, or swelling develops.

In studies, no significant adverse events were reported, even under controlled dry conditions. Report any suspected side effects via the Yellow Card scheme (UK) or equivalent pharmacovigilance systems.

How to store soybean oil eye drops

Proper storage ensures efficacy and safety:

• Keep out of reach and sight of children.
• Store in a cool, dry place away from direct heat, sunlight, or moisture.
• Use opened single-dose units immediately; do not store or reuse, as they lack preservatives and risk bacterial contamination.

Important information about all medicines

General precautions apply:

• Never share eye drops with others.
• Inform your doctor of allergies, especially to soy or eggs.
• Check expiry dates; discard outdated products.
• For full details, consult the product leaflet or healthcare provider.

Frequently Asked Questions (FAQs)

Q: What are soybean oil eye drops used for?

A: They treat dry eyes by acting as artificial tears, relieving soreness and reducing tear evaporation, especially in evaporative dry eye or MGD.

Q: Is Emustil still available?

A: Discontinued in the UK as of 2025; check local availability elsewhere.

Q: How often can I use Emustil?

A: Up to four times a day, one drop per eye.

Q: Do they cause side effects?

A: Unlikely; temporary blurring is common but brief.

Q: Can children use them?

A: Yes, suitable for adults and children.

Q: Are they preservative-free?

A: Yes, in single-use units to prevent contamination.

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