Eye drops, while intended for local treatment, can cause systemic side effects, including nausea. This reaction occurs when the medication does not stay confined to the eye’s surface. The body’s natural drainage system can inadvertently turn a topical treatment into a medication that impacts the entire body. Nausea or an upset stomach signals that the active ingredients have entered the bloodstream or digestive tract.
The Path from Eye to Stomach
The reason eye drops can affect the digestive system lies in the tear drainage system. Tears and excess eye drop solution drain through two small openings called puncta, located in the inner corner of the upper and lower eyelids. These openings lead into the nasolacrimal duct, which connects the eye to the nasal cavity.
The medication travels down the nasolacrimal duct into the back of the nose and throat. Here, two main routes lead to systemic effects. First, the solution can be absorbed directly through the highly vascularized mucous membranes lining the nasal cavity, allowing the drug to enter the bloodstream rapidly.
Second, the solution not absorbed in the nose can be swallowed and pass into the stomach. This absorption route largely bypasses the liver, the body’s primary site for breaking down foreign substances. This means the drug enters the general circulation at a higher concentration than if taken orally, making systemic side effects more likely.
Medications That Commonly Cause Nausea
The likelihood of experiencing nausea depends on the specific drug class and the medication’s chemical properties. Eye drops designed to treat conditions like glaucoma or inflammation are the most common culprits for systemic effects. For instance, topical Carbonic Anhydrase Inhibitors are known to cause a bad taste in the mouth and can lead to an upset stomach or nausea.
Beta-blockers, frequently prescribed to lower intraocular pressure, are also absorbed systemically. They can cause effects like dizziness, fatigue, or a slow heart rate, which may contribute to malaise or nausea. The chemical structure of these drugs makes them readily permeable through mucous membranes, leading to efficient systemic absorption.
Alpha agonists, used to treat high eye pressure, can cause side effects such as dry mouth, dizziness, or weakness. These systemic effects can disrupt the body’s equilibrium, leading to gastrointestinal discomfort. The potential for systemic side effects is relevant for drugs that are highly lipophilic, meaning they dissolve well in fats and easily cross cell membranes into the circulation.
Simple Steps to Reduce Side Effects
Simple, effective techniques minimize the drainage of eye drops into the nose and throat, reducing the risk of systemic side effects like nausea. The most effective method is punctal occlusion, or nasolacrimal occlusion. This involves applying gentle pressure to the inner corner of the eye, next to the nose, immediately after applying the drop.
Maintain this pressure for at least two to three minutes, which effectively blocks the entrance to the nasolacrimal duct and prevents the solution from draining. While performing the occlusion, keep the eyelid gently closed. Closing the eye for two to five minutes after administration significantly reduces the plasma concentration of the drug in the bloodstream.
The eye can only hold a small volume of liquid, typically around 10 microliters. Since most commercial dispensers release a much larger volume, only one drop should be applied per dose. Wipe away any excess medication that spills onto the cheek or eyelid with a clean tissue before opening the eye. Proper technique ensures the medication stays on the surface long enough to be absorbed locally, maximizing therapeutic effect while minimizing systemic reaction.