Phentermine and Glaucoma – Does it affect open and narrow angle glaucoma?

  • By: jacob foxx
  • Date: April 27, 2023
Phentermine and Glaucoma

In recent years, phentermine has become more well-known as an appetite suppressant that doctors recommend for people trying to lose weight safely.

However, studies have suggested a possible link between phentermine and glaucoma, as well as other general eye defects.

It is important to note that high blood pressure has also been associated with an increased risk of eye damage.

For people with glaucoma, it is especially important to be wary of taking phentermine if they already have low blood pressure or take other drugs that increase the risk of developing glaucoma.

Let’s learn more about how phentermine is linked to glaucoma and other basic eye problems.

Does Phentermine Cause Glaucoma?

If you are using phentermine and have open-angle glaucoma, it is important to be vigilant about your eye health.

This weight-loss medication can worsen your condition, leading to dim vision and increased pressure in the eyes.

It is prudent that those with open-angle glaucoma have regular eye checks when taking Phentermine. On the other hand, if you have narrow-angle glaucoma, you should avoid taking phentermine altogether.

The reason is that it can cause a sudden rise in intraocular pressure due to pupil dilation and decreased iris mobility.

What Effect Does Phentermine Have on Glaucoma?

Phentermine has been linked to an increased risk of glaucoma. This condition affects the optic nerve, which can lead to vision loss and blindness if left untreated.

For individuals who already have glaucoma, taking phentermine can worsen symptoms such as dry eyes, blurred vision, and difficulty seeing at night.

The drug’s stimulant action is responsible for most adverse effects on the eyes and glaucoma.

The following are some of the ways Phentermine may influence glaucoma:

1. Stimulation of the Central Nervous System

Phentermine has a profound effect on the central nervous system. Its performance-enhancing properties lead to an increased heart rate and blood pressure. However, in some cases, phentermine can cause an increase in eye pressure.

This added pressure can exacerbate the symptoms of those with existing glaucoma or other preexisting conditions, leading to further complications.

2. High Blood Pressure

Phentermine has been linked to potential eye complications. Specifically, the drug can raise the pressure of blood in the vessels inside the eyes, increasing the risk of retinal and vitreous hemorrhage.

Retinal hemorrhage is characterized by bleeding or hemorrhage in the retina, the part of the eye that senses light and sends images to the brain. Meanwhile, vitreous hemorrhage occurs when fluid from the retina’s capillaries leaks into other areas of the eye, causing vision problems. 

3. Excessive sweating

Phentermine can have the unexpected side effect of increasing sweating. While sweating is a natural bodily function, excessive sweating can cause fluid buildup around the eyes, leading to glaucoma.

Glaucoma is a condition that occurs when excessive fluid builds up and increases pressure in the front chamber of the eye, potentially damaging the optic nerve and resulting in vision loss or blindness if left untreated. 

4. Fluid Buildup

Fluid buildup in the eyes can be a cause for concern, particularly when it comes to the cornea. Excess fluid can easily irritate this delicate structure, resulting in discomfort and even pain.

It is essential to regularly check the cornea for any signs of glaucoma, a disease that can ultimately lead to blindness if left untreated. Unfortunately, glaucoma often develops without any noticeable symptoms until significant damage has already occurred.

5. Boost your light sensitivity

Phentermine has been known to cause an increase in eye pressure and sensitivity to light. Although not an indication of glaucoma, the resulting symptoms of blurred vision and tearing of the eyes can be bothersome for some individuals.

This effect on the eyes should not be taken lightly, and those taking phentermine should always be aware of any changes in their vision.

6. Dilation of the pupils

Phentermine may impact your ability to drive safely through pupil dilation, which can impair your vision in low-light conditions, such as driving at night or in dimly lit areas.

To prevent any potential accidents, it is recommended that individuals take precautionary measures like wearing protective eyewear, such as sunglasses, during the day while taking phentermine.

7. Migraines

Glaucoma can lead to severe headaches. Individuals who are also using Phentermine, a weight loss medication, may experience worsened head pain due to increased blood flow and pressure in the head and neck.

Adding caffeine or alcohol to the mix can further intensify these headaches, making them even more unbearable.

8. Vision Alteration

It’s important to note that taking phentermine can potentially cause vision changes in individuals. While this is a known side effect, it’s particularly concerning for those with glaucoma.

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This group of individuals may experience more severe vision changes, including peripheral vision loss and tunnel vision. For those with glaucoma, seeing near objects may become increasingly difficult, and reading small print may require extra effort. 

9. Increased intraocular pressure

Intraocular pressure (IOP) plays a crucial role in maintaining the structural integrity of our eyes. It acts as a supporting force, preventing our eyes from collapsing under their weight.

However, when the IOP becomes abnormally high, it can lead to damage to crucial structures within the eye, ultimately resulting in vision loss.

Therefore, it is essential to monitor and maintain a healthy IOP to avoid the detrimental effects associated with increased pressure.

As such, regular eye examinations are recommended to ensure that any changes in IOP can be identified and addressed promptly to preserve one’s vision.

Phentermine and Glaucoma with Open Angles

Open-angle glaucoma is a condition that affects millions of people worldwide, making it the most common type of glaucoma.

This condition is characterized by a gradual increase in intraocular pressure, which can eventually lead to serious damage to the optic nerve.

People with open-angle glaucoma should be cautious when taking certain medications, including Phentermine, as it can raise intraocular pressure further and cause unpleasant side effects such as headaches, insomnia, irritability, and anxiety.

There are two forms of POAG primary open-angle glaucoma and secondary open-angle glaucoma, both of which require careful management to prevent further damage to the eyes.

Primary open-angle glaucoma (POAG) and phentermine

Primary open-angle Glaucoma (POAG) is a prevalent eye disorder that affects more women than men. It is caused when the drainage angle between the iris and cornea constricts, leading to augmented eye pressure.

The increased pressure can cause harm to the optic nerve cells resulting in vision loss or blindness eventually.

Though ongoing studies do not give a definitive answer to the effects of Phentermine on POAG, it is known that the drug might increase blood pressure, which may further escalate the eye pressure and cause vision loss.

There are two types of POAG: primary and secondary. It is crucial to monitor your eye health regularly, especially if you are a woman, as POAG can lead to irreversible vision loss.

Secondary open-angle glaucoma (SOAG) and phentermine

Secondary open-angle glaucoma is a type of glaucoma that is caused by increased pressure within the eye, known as intraocular pressure (IOP).

This condition can lead to serious vision problems, including macular degeneration, retinal detachment, and visual impairment.

It is important for individuals who are taking Phentermine and have SOAG to consult a doctor about alternative weight loss methods as it may worsen the condition. There are two types of POAG: primary and secondary.

Narrow-Angle Glaucoma and Phentermine?

Taking Phentermine for weight loss may come with a risk of developing Narrow-angle Glaucoma.

This type of glaucoma occurs when the drainage angle inside the eye is blocked, preventing fluid from draining properly.

Phentermine, a popular weight loss medication, can cause pupil dilation, which may lead to an acute attack of angle-closure glaucoma.

If not treated immediately, this can result in increased pressure in the eye and ultimately, permanent vision loss.

If you have glaucoma, can you take phentermine?

Phentermine, a popular weight loss drug, has been linked to an increased risk of glaucoma and other side effects. It is crucial to take the necessary precautions when using this medication.

One should avoid taking it for more than three months, use the lowest possible dose, and schedule regular eye exams to monitor vision and eye health.

Pregnant or breastfeeding women should not take Phentermine, and it should not be mixed with alcohol, caffeine, or amphetamines.

Before taking it, always follow the instructions on the bottle and consult with a doctor who has experience with Phentermine and glaucoma.

As always, other diet pills may prove to be more effective and a safer alternative.

What Is a Glaucoma-Friendly Diet Pill?

Phentermine, a weight loss drug that has been on the market for decades, can have serious side effects for those with glaucoma.

Its use is not recommended for these individuals due to its potential to increase eye pressure, which can cause further damage to the optic nerve.

Fortunately, there is an all-natural alternative that can support weight loss without any negative impact on blood pressure or other health issues. PhenQ is a prescription-free diet supplement that boasts all-natural ingredients, making it safe to take without any adverse reactions.

And the best part? You don’t even need a prescription to try it out. If you’re looking for a weight loss solution that is effective and safe, PhenQ may be just the thing you need.

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click to find out more about PhenQ


If I Have Glaucoma, Should I Take Phentermine?

According to sources, the use of most CNS stimulants, including Phentermine, is contraindicated in patients with Glaucoma due to the sympathomimetic activity that can induce mydriasis, which can provoke eye pressure.

Moreover, experts from the National Eye Institute advise that people with Glaucoma should not take Phentermine or any other drug that may raise eye pressure to avoid aggravating the situation.

Therefore, if you have Glaucoma, it is best to avoid taking Phentermine, as it can increase your eye pressure and potentially worsen your condition. Instead, you can try other healthy lifestyle choices such as a balanced diet and regular exercise to achieve your weight loss goals.

Can Phentermine Raise Eye Pressure?

Yes, phentermine can raise eye pressure in some individuals who take it. This temporary increase in pressure may lead to acute symptoms such as blurred distance vision or pain.

Patients with narrow angles have a higher risk of developing acute angle closure after pupillary dilation. Additionally, weight loss drugs containing topiramate have been associated with the development of bilateral acute angle closure4.

Can Phentermine Make Your Eyes Dry?

Yes, Phentermine has been known to cause dry eyes as a common side effect. While the ocular effects of Phentermine may be annoying, certain measures can be taken to manage this symptom, such as using artificial tears.

However, it is important to note that in some cases, Phentermine can also have severe ocular effects, such as ciliary body detachment and lasting eyesight loss.

Does phentermine impair your vision?

Yes, phentermine can mess with your vision as a side effect. Some individuals may experience blurred vision, dry eyes, or changes in their vision such as trouble focusing or double vision while taking phentermine. In rare cases, phentermine has been associated with more severe ocular complications such as glaucoma, cataracts, or even permanent vision loss.

What are the significant eye effects of Phentermine?

Phentermine, like other medications, can have both mild and severe ocular side effects in some individuals. The significant eye effects of Phentermine that have been reported include:

  • Dry eyes: Phentermine can decrease tear production, causing dry eyes and discomfort.
  • Blurred vision: Some individuals may experience blurred vision or trouble focusing while taking Phentermine.
  • Mydriasis: Phentermine can cause pupils to dilate, increasing the risk of acute angle-closure glaucoma in those with narrow-angle glaucoma.
  • Decrease in night vision: Phentermine may also decrease your ability to see in low-light situations, making driving at night more challenging.
  • Detached retina: In rare cases, Phentermine has been associated with ciliary body detachment, causing lasting eyesight loss.

It is important to remember that not everyone experiences these side effects, and these side effects may go away once you stop taking Phentermine. If you experience any concerning ocular effects during Phentermine treatment, you should contact your doctor immediately.


As with any medication, it is important to be aware of potential risks and suitability before starting treatment.

Recent studies have suggested that the use of Phentermine may increase the risk of glaucoma, highlighting the importance of more research in this area.

Those with high blood pressure should consult a doctor before taking this medication. If you are considering the use of Phentermine, it is crucial to inform your doctor about any existing health conditions and ask for any precautionary measures to take.

It may also be worth considering alternative options, such as PhenQ, which could be a safer and more suitable option for some individuals. 

click to find out more about PhenQ

I'm Jacob Foxx, a proud native of the outskirts of Chicago, Illinois. I was enamored with the expansive Star Trek universe and its promise of cutting-edge technology and space travel from a young age. This early fascination with science fiction sparked my imagination and laid the foundation for my writing career. Alongside my love for the cosmos, I developed a passion for fitness in my formative years.

This dual interest in the world of tomorrow and the pursuit of physical health has greatly informed my writing, allowing me to explore themes of human potential and the future of our species. As an author, I strive to blend these passions into compelling narratives that inspire readers to dream and to push their own boundaries.

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