While eye drops are safe and effective for their intended use in the eyes, many of their active ingredients can have harmful systemic effects when absorbed through the gastrointestinal tract.
Ingredients commonly found in eye drops, such as decongestants (e.g., tetrahydrozoline and naphazoline), preservatives (e.g., benzalkonium chloride), and certain other chemicals (e.g., boric acid), are not safe for ingestion.
These substances can lead to serious adverse effects, such as cardiovascular depression, a marked decrease in blood pressure and heart rate, CNS depression, nausea, vomiting, and in severe cases, potentially life-threatening conditions. Conversely, some ingredients like lubricants (e.g., polyethylene glycol) may be less harmful but can still cause discomfort or gastrointestinal upset when ingested in significant amounts.
It’s important to treat any case of accidental ingestion of eye drops as a potential medical emergency, especially in vulnerable populations such as children and the elderly, who are at a higher risk of experiencing severe symptoms.
Immediate steps should include contacting a poison control center at 1-800-222-1222 for their intervention in the situation. Typically, the treatment will depend on the specific ingredients ingested, the amount, and the individual’s condition.
Safety Of Common Ingredients In Eye Drops Upon Ingestion
1. Tetrahydrozoline: Toxic
Tetrahydrozoline is a vasoconstrictor used in eye drops to reduce redness by narrowing blood vessels. When ingested, it can lead to serious systemic adverse effects due to its action on the cardiovascular and central nervous systems.
According to a study conducted by BMJ Case Reports, Visine eye drops containing tetrahydrozoline have been shown to cause first-degree and third-degree heart block. Other brands containing tetrahydrozoline include Walgreens Redness Relief, Leader Eye Drops, Opti-clear, and GNP Original. There is a prevalence of pediatric cases in the ingestion of these imidazole-based products.
Symptoms of ingestion can include severe hypotension (low blood pressure), bradycardia (slow heart rate), lethargy, hypothermia, and, in extreme cases, coma. Its mechanism of action when absorbed systemically can mimic an overdose of alpha-adrenergic agonists, which are substances that can cause a significant decrease in the activity of the heart and brain.
2. Naphazoline: Toxic
Similar to tetrahydrozoline, naphazoline is another decongestant that works by narrowing swollen blood vessels in the eyes to reduce redness and swelling. If ingested or misused, they can lose their selectivity as an alpha2-adrenergic agonist leading to acute poisoning.
Clinical features of acute naphazoline toxicity include marked hypotension, skin pallor, weakness, and potentially life-threatening effects, like central nervous system depression and heart failure. Children and individuals with pre-existing health conditions are at greater risk of acute toxicity.
3. Carboxymethylcellulose: Safe
Carboxymethylcellulose is a lubricant used in eye drops to relieve dryness and irritation. It is a cellulose derivative that is generally considered safe for ocular use.
While it is not known to be significantly harmful, consuming large quantities could potentially lead to gastrointestinal upset or discomfort due to its water-absorbing properties, leading to an expansion in the digestive tract.
Research suggests that carboxymethylcellulose can cause bacterial overgrowth and mild inflammation of the small intestine in genetically predisposed mice.
4. Polyvinyl Alcohol: Safe
Polyvinyl alcohol (PVA) is another viscosity-enhancing agent used in eye drops. It is generally safe upon ingestion in small quantities, as it is not extensively absorbed by the digestive system. PVA is also used in other medical and cosmetic products, indicating its relatively benign safety profile.
Ingesting it in the form of eye drops or quantities not intended for oral consumption could potentially lead to adverse effects. Besides, different formulations of eye drops contain other harmful ingredients.
5. Polyethylene Glycol: Safe
6. Benzalkonium Chloride: Toxic
Benzalkonium chloride is a preservative and antimicrobial agent used in many eye drops. It is not safe for ingestion as it can cause poisoning, with symptoms including nausea, vomiting, and mucosal irritation. In severe cases, it can lead to systemic toxicity affecting the central nervous system and cardiovascular system.
7. Propylene Glycol: Safe In Moderate Amount
Polyethylene glycol (PEG) is safe for ingestion in the doses typically found in eye drops, as it is also an active ingredient in oral laxatives. It works by retaining water in the stool to induce bowel movements. While generally safe, ingesting large quantities of PEG, especially in a concentrated form, could lead to diarrhea, nausea, and abdominal bloating.
Propylene glycol is used as a solvent and conditioning agent in eye drops. It is considered safe in moderate amounts upon ingestion and is also used in food and pharmaceutical products. However, consuming large quantities can lead to central nervous system depression, and in very high doses, it could cause lactic acidosis, a condition that occurs when there’s too much lactic acid in the body.
8. Boric Acid: Toxic
Boric acid has antiseptic and antimicrobial properties but is not safe for ingestion. It can cause nausea, vomiting, diarrhea, and abdominal pain. In more severe cases, it can lead to renal failure, shock, and even death. Its toxicity is due to its interference with the body’s metabolic processes.
9. Povidone: Safe
Povidone (polyvinylpyrrolidone or PVP) is used as a lubricant and a binder in eye drops and other pharmaceutical formulations. It is considered safe for ingestion in small amounts and is commonly used in oral medications. While generally well-tolerated, consuming large quantities of povidone can potentially cause gastrointestinal distress.
What To Do If You Accidentally Ingested Eye Drops
Accidental ingestion of eye drops is a situation that requires prompt and careful attention due to the potential risks associated with the systemic absorption of their ingredients. Here’s what you should do and what to expect if you or someone else accidentally ingests eye drops:
1. Gather Vital Details About The Incident
Quickly collect all relevant information about the incident. This includes:
- The brand and specific type of eye drops ingested.
- The active ingredients listed on the product label and their concentrations if available.
- The age, weight, and any underlying health conditions of the person who ingested the eye drops.
- An estimate of the amount swallowed.
- The time of ingestion.
2. Call the Poison Control Center Or 911
Immediately contact a poison control center at 1-800-222-1222 for guidance on the next steps. If the person is unconscious, or showing signs of severe distress, if advised by the poison control center number, call 911 to get medical help right away.
Do not try to make the person vomit unless you are explicitly instructed to do so by a medical professional. Inducing vomiting inappropriately can cause further harm.
What To Expect From The Emergency Room?
Upon arrival at the emergency room, medical staff will assess the situation based on the information provided and the patient’s condition. The treatment approach may include:
Vital signs will be monitored, including heart rate, blood pressure, respiratory rate, and oxygen saturation. A physical examination will be performed to assess the patient’s overall condition.
If the ingestion was very recent, activated charcoal may be administered to absorb the substances and reduce absorption from the gastrointestinal tract.
The medical team will provide treatment to manage symptoms and stabilize the patient. This might include intravenous fluids, medications to support blood pressure and heart rate, and other supportive measures as needed.
The patient may be observed for a period to monitor for the development of any symptoms or complications.
Prognosis For Ingestion Of Eye Drops
The prognosis following the accidental ingestion of eye drops largely depends on several factors:
Some ingredients pose a higher risk than others. Small quantities may have minimal effects, while larger doses can be more dangerous.
Prompt medical intervention can significantly improve the prognosis by limiting the absorption of toxic substances and addressing any symptoms early.
Age, weight, and pre-existing health conditions can influence how the body reacts to the ingestion and the severity of the outcome.
