Why Does Phentermine Cause Blurry Vision?

Phentermine is a prescription medication commonly used to help with weight loss by suppressing appetite. However, like other medications, it also comes with a range of possible side effects, one of which includes blurry vision.

To understand why phentermine causes blurry vision, we need to look at how the drug affects the body. This side effect can be especially worrying for people who need clear vision for their daily tasks.

In today’s article, we will discuss the mechanisms by which phentermine can lead to blurry vision and examine the physiological effects of the drug on ocular health. We will also explore how patients can manage and mitigate this side effect to maintain their quality of life.

Why Does Phentermine Cause Blurry Vision

Table of Contents

Understanding Phentermine and Its Side Effects

What is Phentermine?

Phentermine is a sympathomimetic amine, which means it mimics the actions of the sympathetic nervous system. Essentially, it stimulates the release of neurotransmitters like norepinephrine and dopamine, which helps by curbing your appetite.

The drug mainly affects the central nervous system, leading to increased heart rate, blood pressure, and energy levels. While effective for weight loss, these changes in the body’s equilibrium can cause various side effects, including anxiety, insomnia, and indeed, blurry vision.

Common Side Effects

Here are some of the possible side effects that people may experience when taking phentermine:

Dry mouth
Headaches
Dizziness

Nausea and vomiting
Increased heart rate
Diarrhea or constipation

Changes in libido
Insomnia

These side effects can be different for everyone, but they usually go away once your body gets used to the medicine.

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Why Does Phentermine Make Your Vision Blurry?

Pupil dilation and changes in blood flow are some of the ways phentermine can affect your vision.

Another important factor is the drug’s influence on intraocular pressure (IOP) or eye pressure. Phentermine can potentially increase IOP, especially in people predisposed to conditions like glaucoma. Elevated IOP can damage the optic nerve, potentially causing blurry vision or even permanent vision loss if not treated.

Another reason is that dry mouth is a common side effect that can also lead to dry eyes. When less saliva is made, it also means fewer tears are produced. Tears are important for keeping our eyes moist and clear. Without enough tears, our eyes can feel uncomfortable and irritated, and our vision can become blurry.

Lastly, Acute angle-closure glaucoma is a more serious side effect that can happen to some people taking phentermine. It occurs when the colored part of your eye (the iris) gets pushed forward which blocks the fluid from draining out of the eye. This can cause a sudden rise in eye pressure, leading to blurry vision, severe eye pain, headache, nausea, and vomiting. If you experience any of these symptoms, seek immediate medical attention.

RELATED: Why Does Phentermine Make You Pee a Lot?

Case Study: Real-Life Example of Phentermine-Induced Blurry Vision

According to KoreMed Synapse, a 25-year-old woman came to our hospital with blurry vision and eye pain after taking phentermine hydrochloride for 3 weeks [1]

An eye exam showed a shift towards nearsightedness in both eyes, the lens and iris were pushed forward, and the retina had folds.

We suspected the drug caused these issues, so we stopped the medication and gave her some eye drops to relax the eye muscles and lower eye pressure. Thankfully, her symptoms improved with this treatment.

However, long-term use of phentermine can lead to permanent vision loss, so the patient was warned against its continued usage.

Although the exact reason isn’t clear, they believe that phentermine hydrochloride can cause fluid buildup and swelling in the eye, leading to sudden nearsightedness and angle closure due to the lens and iris moving forward.

How to Manage Blurry Vision While Taking Phentermine

While doctors still do not understand the exact mechanism behind phentermine-induced blurry vision, there are some steps you can take to manage this side effect:

Regular Eye Exams: Make sure to have your eyes checked regularly to keep track of your eye health and catch any problems early. This is especially important if you already have an eye condition or are at risk for glaucoma.
Stay Hydrated: Make sure you drink enough water. Staying hydrated can help prevent dry mouth and dry eyes which can cause blurry vision.

Use Artificial Tears: Over-the-counter artificial tears can help keep your eyes moist and reduce irritation and dryness which can improve your vision clarity.
Monitor Symptoms: Notice any changes in your vision or how your eyes feel and tell your doctor right away. It’s important to get help quickly if you have bad eye pain, headaches, feel sick, or throw up.
Wear Protective Eyewear: In environments where your eyes could be exposed to irritants or strain (like bright sunlight or screens), wear protective eyewear to reduce eye stress.

Limit Screen Time: Reduce the amount of time spent on screens. Take regular breaks to prevent eye strain and allow your eyes to rest.
Follow a Balanced Diet: Consuming a diet rich in vitamins and nutrients that support eye health, like leafy greens, omega-3 fatty acids, and vitamins A, C, and E, can be beneficial.
Manage Underlying Conditions: Ensure that other health conditions that could affect your eyes, like hypertension or diabetes, are well-managed.

Conclusion

In conclusion, phentermine can be an effective tool for weight loss, but it is not without its risks, particularly when it concerns vision health. By understanding the potential side effects, like blurry vision, and taking steps to watch and handle these issues, patients can reduce risks and keep their quality of life.

Regular eye exams, staying hydrated, using artificial tears, and keeping an eye on vision changes are important. Always talk to professionals quickly if you have serious symptoms to get the right care.