Contraindications of Sildenafil: A Guide for Safe Use

Published On
Updated On
Written By Julie Ingram
contraindications of sildenafil

Sildenafil, also known as Viagra, is a medicine used for Erectile Dysfunction treatment in males. Approved by FDA in 1998, it is the most prescribed medicine for ED. It is highly researched, well-tested, and generally safe for most people.

Like every medicine, Sildenafil interacts with a few other drugs, conditions, and food.

These interactions can affect Sildenafil’s effectiveness or cause contraindications.

Contraindications of Sildenafil refer to the conditions or circumstances under which this medication is not recommended or could be harmful.

This article will discuss the contraindications of Sildenafil (Viagra) with medical conditions and medication. 

Who cannot take Sildenafil

Sildenafil (Viagra) is a prescription drug and is not recommended to everyone. 

Sildenafil is a PDE5 inhibitor, which dilates blood vessels. It works by blocking the PDE5 from destroying cGMP.

cGMP relaxes blood vessels in the penis and improves blood flow, which results in an erection.

Although Sildenafil is generally safe, some people should avoid it. These include pregnant or lactating women, people taking certain medications, or having certain medical conditions.

Individuals having pre-existing medical conditions

Heart attackSource: pixelshot
Heart attack

Certain medical conditions may prevent someone from taking Sildenafil (Viagra). These medical conditions can cause contraindications with Sildenafil and induce side effects

Some of these medical conditions include cardiovascular diseases, Angina, liver or kidney disease, etc.

Here is a detailed explanation of some of these medical conditions:

Cardiovascular diseases: Sildenafil widens the blood vessels in the heart, increasing blood flow. This can put excess strain on the heart. Young and healthy adults are generally safe from this excess strain. Some serious side effects have been reported in older adults. People with heart disease should be cautious while taking Sildenafil.

Unstable Angina: Unstable Angina is a chest pain that occurs suddenly, often at rest or with minimal physical work. It is an early sign of a heart attack. Sildenafil can worsen it by dilating blood vessels and making it life-threatening. It can also interact with medication used to treat Angina.

Heart attack or recent stroke: If you have recently experienced a stroke or heart attack, your cardiovascular system is still weak. Taking Sildenafil during this period may increase the risk of another one. It is essential to wait for an appropriate recovery period, usually several months.

Severe liver or kidney disease: Sildenafil is metabolized in the liver and eliminated through the kidneys. The drug may not be metabolized or excreted properly if these organs are not working correctly. It will cause Sildenafil to build up in the body and increase the risk of side effects. 

Retinitis Pigmentosa: It is a rare genetic eye disease affecting the retina’s light-sensitive cells. It leads to progressive vision loss. Sildenafil may worsen the condition by increasing blood flow to the retina.

Blood disorders: Sildenafil affects blood flow, which may be problematic for people with sickle cell anemia or leukemia. It may cause Priapism. Priapism is a painful erection that lasts longer than four hours without sexual stimulation.

Penis deformity: In people with a Penis Deformity (PD), the increased blood flow to the penis can worsen the deformity. This deformity might cause pain during erections. Although there is a potential risk of pain there is no evidence that it will worsen. There is a study that concludes that continuous use of oral PDE5 inhibitors may be a potential treatment for PD. However, more controlled studies are needed.

To get into more details, read this articleIs Viagra Helpful for treating Peyronie’s Disease

Stomach ulcers or bleeding disorders: Sildenafil may increase the risk of bleeding in people with stomach ulcers or hemophilia. The increased blood flow can worsen existing ulcers or cause excessive bleeding in individuals with bleeding disorders.

Curious about whether Sildenafil affects male fertility or not? Get the answer in this article- Sildenafil’s Impact on Fertility and Reproductive Health

Please note that this is not a complete list of medical conditions to avoid Sildenafil. Other conditions may contraindicate with Sildenafil. It is essential to consult your doctor before starting any new medication.

Individuals taking specific medicines

Certain medications can interact with Sildenafil and cause side effects. Some of these medications can not be taken at all to avoid contraindications, and some should be taken in low doses.

Some of the medications that you should avoid taking with Sildenafil:

Nitrates: Nitrates like Nitroglycerin and Isosorbide Dinitrate are used to treat chest pain. When taken with Sildenafil (Viagra), it can cause a drop in blood pressure. This drop in blood pressure will lead to dizziness and fainting. 

For more in-depth exploration of this topic, refer to this articleA Dangerous Mix: Viagra and Nitroglycerin

Alpha-blockers: Medications used to treat high blood pressure and enlarged prostate. Taking these medications with Sildenafil can cause dizziness and fainting. Some examples of Alpha-blockers are Tamsulosin, Prazosin, and Doxazosin.

Protease inhibitors: A class of medications used to treat viral infections like Hepatitis C and HIV. When taken with Sildenafil, it can cause an increase in Sildenafil’s level in the blood.

Other PDE5 inhibitors: Sildenafil is a PDE5 inhibitor. Taking other PDE5 inhibitors like Tadalafil, and Vardenafil along with Sildenafil will drop the blood pressure to a dangerous level.

Eager to know the differences between Sildenafil and other PDE5 inhibitors? Delve into these articles:

Tadalafil vs Sildenafil – Which ED Pill Reigns Supreme
Vardenafil vs Sildenafil: A Head-to-Head Comparison

CYP3A4 inhibitors: Medications that block an enzyme in the liver called CYP3A4. This enzyme metabolizes drugs like Clarithromycin, Erythromycin, Itraconazole, and Ketoconazole. These combination can increase the level of Sildenafil in the blood, leading to adverse effects.

This list doesn’t cover all medications. For a comprehensive guide, check out this article6 Drugs not to take with Viagra (Sildenafil) at all costs

Order Now:
Take your first step towards a more fulfilling, stress-free romantic life today:

  • Shop Cenforce
  • Shop Kamagra
  • Shop Suhagra
  • Males below 18 years of age

    As per FDA, the age restriction for taking Sildenafil is 18 years and above. It is not advised for use in children and adolescents under 18.

    Sildenafil has not been well studied in individuals below 18. There may be potential risks and side effects that are specific to younger individuals.

    Younger individuals below 18 are still in a stage of physical and sexual development. It is important to allow natural development to occur without the use of medications.

    No matter your age, health, or fitness, always consult a doctor before taking Sildenafil. Follow the prescribed dosage and directions of use to avoid any contraindications of Sildenafil.

    Pregnant or lactating women

    FDA has not yet approved Sildenafil for use in women. But doctors still prescribe it for use in women, known as its off-label use.

    Some studies suggest that Sildenafil may help women with sexual arousal disorder. However, these results are inconclusive, and more research is needed.

    Lovergra is a generic Sildenafil prescribed for Female Sexual Dysfunction (FSD).

    Sildenafil is usually not prescribed to pregnant or lactating women. 

    The safety of Sildenafil for women during pregnancy or breastfeeding is not yet studied in humans.


    Sildenafil is an FDA-approved medicine for treating ED. It is highly tested and well-researched. But it can still interact with certain drugs and cause contraindications. 

    Contraindication is a condition in which taking medication can be harmful. Contraindications of Sildenafil can cause mild to serious side effects.

    In certain medical conditions, you should avoid Sildenafil. These conditions include cardiovascular disease, liver or kidney disease, and blood disorder.

    Certain drugs can interact with Sildenafil. These drugs include Nitrate, Alpha-blockers, Protease inhibitors, etc.

    Anyone above 18 can take Sildenafil with a doctor’s prescription. Older people may need a lower dose of Sildenafil.

    Frequently Asked Questions

    Can Sildenafil interact with certain types of food or drink?

    Yes, Sildenafil can interact with certain types of food and drink. These include grapefruit, high-fat meals, and alcohol. 
    Grapefruit juice can increase the levels of Sildenafil in the body. A high-fat meal with Sildenafil can delay the drug’s absorption. 
    Alcohol with Sildenafil can cause dizziness, lightheadedness, and low blood pressure.

    Are there any age restrictions for taking Sildenafil?

    Yes, there are age restrictions for taking Sildenafil. It is only approved for use in men 18 years and older. 
    Older people may need a lower dose. A doctor may prescribe it off-label to younger males in certain cases.

    How long does the effects of Sildenafil last?

    The effects of Sildenafil usually last for around 4 hours. However, the duration of its effect can vary depending on factors such as age, dosage, and individual response.

    Does Sildenafil increase the risk of sexually transmitted infections?

    No, Sildenafil does not increase the risk of sexually transmitted infections (STIs). 
    However, engaging in sexual activity can increase the risk of STIs. Using a condom during sexual activity can help reduce the risk of STIs.

    Can Sildenafil cause allergic reactions?

    Yes, Sildenafil can cause allergic reactions in some people. An allergic reaction to Sildenafil includes rash, itching, swelling, dizziness, and trouble breathing. 
    If you experience these symptoms, seek medical attention immediately.

    What should I do if I experience side effects from Sildenafil?

    If you experience side effects from Sildenafil, stop taking it and seek medical attention immediately. Some common side effects include headache, facial flushing, nasal congestion, and indigestion.

    When quoting information, ForDailyMedicine always provides full citations. Please read our Content Information Policy if you want more details on the methods we take to ensure the continued high quality of our content.