Viagra side effects and how to avoid them

Viagra side effects | Serious side effects | Blood pressure | Vision loss | How long do side effects last? | Warnings | Interactions | How to avoid side effects

Viagra is a brand-name prescription drug approved for the treatment of erectile dysfunction. Sildenafil citrate, the active ingredient in Viagra, belongs to a class of drugs called phosphodiesterase type 5 inhibitors, or PDE5 inhibitors, for short. Viagra works by widening blood vessels in the penis, increasing and prolonging blood flow into the penile erectile tissues. Viagra, however, can cause problems in some men, such as side effects or drug interactions. Viagra can also worsen pre-existing conditions. There are ways, however, to minimize some of these risks.

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Common side effects of Viagra

The most common side effects of Viagra are:

• Headache
• Diarrhea
• Nausea
• Stomach upset
• Nosebleed
• Rhinitis
• Nasal congestion
• Flushing
• Skin redness
• Blurred vision
• Skin rash

Serious side effects of Viagra

The most serious side effects of Viagra include:

• Cardiovascular events such as:
  • Chest pain (angina)
  • Heart attack
  • Irregular heartbeats (arrhythmias)
• Severe bleeding (hemorrhage) in the brain, lungs, or eye
• Vision loss
• Hearing loss
• Painful or prolonged erections (priapism)
• Seizures
• Low blood pressure
• Low blood cell counts
• Severe allergic reactions
• Sudden death

Viagra and blood pressure

Viagra and similar drugs were originally invented to lower blood pressure in people with pulmonary arterial hypertension, or high blood pressure in the lung’s arteries. In fact, Pfizer, the manufacturer of Viagra, also markets another sildenafil drug called Revatio that is only used to treat pulmonary hypertension. Because Viagra lowers blood pressure, it can cause problems if blood pressure falls too far. At its mildest, low blood pressure can cause many of the common side effects of Viagra such as fainting, dizziness, lightheadedness when standing, accidental falls, or accidental injuries. Clinically significant low blood pressure, however, has only been reported when people have taken Viagra along with other blood pressure medications, particularly alpha blockers.

Viagra and vision loss

Vision loss has been reported in people taking drugs like Viagra and Cialis. Nearly all cases were due to non-arteritic anterior ischemic optic neuropathy or NAION, a medical condition in which the flow of blood to the optic nerve is stopped. NAION can quickly cause a sudden decrease or complete loss of vision in one or both eyes. Fortunately, NAION is only rarely reported. Unfortunately, it is so rare that not all doctors will screen for this issue. Make sure you share any personal or family history of vision changes with your doctor. People taking Viagra are urged to get immediate medical help if they experience vision changes.

How long do side effects last?

Most of Viagra’s commonly experienced side effects are temporary. Sildenafil has a half-life of about four hours, so headache, nausea, stomach upset, and similar unpleasant side effects should go away in about 4-12 hours. 

Other side effects, such as painful or prolonged erections, loss of hearing, vision changes, severe allergic reactions, stroke, and cardiovascular events will require immediate medical attention. They all have the potential for causing chronic and even lifelong complications. Vision loss due to NAION will be permanent.

Viagra contraindications & warnings

Viagra and similar drugs may not be suitable for everyone. Besides side effects, Viagra can cause problems in people with pre-existing conditions. Other potential problems include abuse or overdose. 

Abuse and dependence

Most healthcare professionals do not think Viagra and similar drugs cause physical dependence, tolerance, or withdrawal. However, Viagra and other erectile dysfunction medications (EDMs) are commonly abused, usually by young men engaged in high levels of sexual activity with multiple partners. These men often use recreational drugs that can cause erectile dysfunction, making chronic use of EDMs necessary. While side effects are a concern, sexually transmitted diseases and potential drug interactions with other illicit or recreational drugs are a greater concern. 

While Viagra does not cause physical dependence, the chronic overuse of EDMs can rise to the level of substance abuse disorder. Ending the abuse may require therapy or treatment.

Overdose

An overdose of Viagra will increase the likelihood and severity of side effects. Call a poison helpline or seek emergency medical attention if an overdose is suspected. 

Restrictions

Viagra may cause problems in people with pre-existing medical or physical conditions. Some people can take Viagra, but their pre-existing conditions may require some caution. Usually, the healthcare provider will monitor the patient more closely. The goal is to spot problems before they become major medical issues. 

• Because sexual activity raises the risk of heart or bleeding problems, Viagra is used cautiously and with extra monitoring in anyone who has had recent symptomatic cardiovascular or vascular problems such as heart attack, stroke, heart disease, heart failure, or similar disorders in the last 6 months.
• Because of the risk of sudden and permanent vision loss, healthcare providers will prescribe Viagra with great caution to anyone with a history of non-arteritic anterior ischemic neuropathy (NAION) or risk factors for NAION such as optic disk crowding or a family history of degenerative retinal disorders, particularly retinitis pigmentosa.
• Healthcare providers will be cautious about prescribing Viagra to people with blood pressure problems including high or low blood pressure, pulmonary hypertension, low blood volume, obstructions to blood flowing out of the heart, and any inability of the body to regulate blood pressure.
• Sildenafil can cause painful erections, so it is generally avoided in men with penile deformities (Peyronie’s disease, cavernosal fibrosis, or angulation) or other conditions that increase the risk for priapism such as sickle cell anemia, leukemia, or multiple myeloma.
• Sildenafil is associated with bleeding events, so people with bleeding problems will be prescribed Viagra cautiously and may need extra monitoring.
• Because sildenafil is broken down by the liver and excreted in the urine, people with severe kidney disease or liver problems may need to be monitored or have doses reduced.

Pregnancy and breastfeeding

Viagra is not prescribed to women, so its safety during pregnancy or breastfeeding has not been studied. If your doctor recommends the use of another sildenafil product, like Revatio, during pregnancy, they will weigh the risks of untreated pulmonary arterial hypertension to the potential benefits of the drug. There is only limited safety data for this scenario. 

Children

The U.S. Food and Drug Administration (FDA) has not approved Viagra for use in anyone younger than 18.

Seniors

Sexual activity raises the risk of heart or vascular problems such as heart attack and stroke. For this reason, Viagra is used with caution in men older than the age of 50. Men with circulatory or heart problems may need to weigh the benefits and risks of sexual activity with a healthcare provider before taking Viagra.

Viagra interactions

Viagra has several interactions that can cause problems. This includes food. While Viagra can be taken with a meal, grapefruit or grapefruit juice should be avoided. Grapefruit has substances that block the liver enzyme that breaks down sildenafil, raising the risk of side effects.

The menu should also not include alcohol, or at least not very much. Alcohol lowers blood pressure, so combining it with drugs that lower blood pressure, like Viagra, can cause blood pressure to dip too low. In addition, alcohol worsens erectile dysfunction, neutralizing any benefit that Viagra has to offer.

Because of potentially serious side effects, people taking Viagra should be well aware of what prescription and over-the-counter drugs can cause problems when taken with Viagra. Some drugs should never be taken with Viagra because the hazards are too great, while others can be taken but require extra monitoring.

Drugs that are contraindicated with Viagra and should never be taken in conjunction are:

• Nitrates
• Guanylate cyclase (GC) stimulators such as Adempas (riociguat) and Verquvo 
• Nitrites, alpha blockers, and blood pressure medications can increase the risk of low blood pressure if taken with Viagra. 
• Do not combine other erectile dysfunction medications (EDMs) with Viagra. Some include Cialis (tadalafil), Levitra (vardenafil), or alprostadil.

Drugs that should be used cautiously in patients taking Viagra include:

• Antibiotics such as erythromycin
• HIV medications such as ritonavir and saquinavir
• Antifungals like ketoconazole and itraconazole)
• Benzodiazepines
• Corticosteroids

How to avoid Viagra side effects

Many men will experience side effects when taking Viagra, but a few tips can ensure that this medicine is taken safely. 

1. Take Viagra only under the care of a healthcare provider

To minimize side effects, the place to start is by getting a prescription from a licensed healthcare provider who performs an in-person physical examination and a complete medical history.

2. Tell the doctor about all medical conditions and medications

When a licensed healthcare provider is performing an in-person physical examination, make sure that person is informed about all current and previous medical conditions. The most important conditions they need to know about are:

• Heart problems
• Recent heart surgery
• Stroke
• Blood pressure problems
• Pulmonary hypertension
• Bleeding problems
• Blood cell disorders such as sickle cell anemia or leukemia
• Stomach ulcers
• Eye problems, especially personal or family history of retinitis pigmentosa or vision loss
• Liver problems
• Kidney problems
• Abnormal penis shape
• A history of prolonged (>4 hours) erections
• Any history of alcohol abuse 
• All medications, over-the-counter medications, supplements, and remedies being taken

3. Only purchase Viagra from a licensed pharmacist

Once you have a prescription, only purchase the medicine from a licensed pharmacist, preferably from the pharmacy that has all your records. Purchasing Viagra or other erectile dysfunction medications through alternative channels—especially the internet—could result in the purchase of counterfeit, unsafe, or improperly dosed medications. Some improperly purchased medications won’t work at all, some will increase the risk of side effects.

4. Take Viagra as directed

Once the Viagra prescription has been filled by a licensed pharmacy, take the dose as prescribed, usually 25–100 mg taken at least 30 minutes before sexual activity. Never take more than prescribed. Never take more than one dose each day. 

5. Avoid grapefruit and grapefruit juice

While Viagra can be taken with food, grapefruit and grapefruit juice should be avoided on the day a dose is taken. Grapefruit has substances that slow down the breakdown of sildenafil in the body, raising the risk of side effects, including some of the worst side effects.

6. Do not drink too much alcohol

Both Viagra and alcohol lower blood pressure, so the combination could cause side effects such as dizziness and fainting. More importantly, alcohol worsens erectile dysfunction. Drinking does help by lowering inhibitions, but it also works against Viagra.

Resources for Viagra side effects:

• Sildenafil compound summary, U.S. National Library of Medicine
• Sildenafil citrate drug summary, Prescriber’s Digital Reference
• Recreational use of erectile dysfunction medications in undergraduate men in the United States: Characteristics and associated risk factors, Archives of Sexual Behaviors
• Recreational Viagra use and sexual risk among drug abusing men, American Journal of Infectious Diseases
• The synergistic (MARATHON) effect of combined methamphetamine with sexual stimulant drugs on increasing the likelihood of high-risk sexual behaviors, Addiction & Health
• Treatment of nonarteritic anterior ischemic optic neuropathy, Survey of Ophthalmology
• Viagra, Epocrates
• Viagra prescribing information, U.S. National Library of Medicine