What Exactly Does Viagra Do In Your Body?

Erectile dysfunction (ED) can be an upsetting and distressing condition and impact relationships. However, your doctor can treat and manage the issue.

Several highly effective treatments can help you regain erectile function. One of these is a medication called Viagra. 

What is Viagra, and what does it do?

Viagra is an oral prescription drug for ED. The generic name is sildenafil. Other brand names of sildenafil include Aronix, Liberize, Nipatra, Revatio, and Granpidam. Not all are for treating ED. 

The role of Viagra is to increase blood flow to the penis, a critical component of having an erection. 

Viagra falls under a category of medications called phosphodiesterase-5 inhibitors (PDE5 inhibitors).¹ 

PDE5 is a naturally-occurring enzyme that blocks cGMP, the protein responsible for causing erections. Viagra prevents PDE5 from having a negative effect on erections and allows cGMP to work on relaxing the smooth muscle in the penis.

Does Viagra treat ED?

ED is the persistent inability to achieve or maintain an erection firm enough for satisfactory sexual intercourse. 

The Food and Drug Administration (FDA) approved Viagra for the treatment of ED in people with a penis over the age of 18. 

Research² has shown that Viagra improves the firmness, frequency, and maintenance of erections. It also indirectly enhances other aspects of relationships, which ED can damage, including:

• The frequency and level of desire in relationships

• The satisfaction and enjoyment of sex

• Overall relationship satisfaction 

Numerous studies have backed up the effectiveness of Viagra, such as: 

• One study³ on men with ED found that more than 94% of the participants were satisfied with the effect that Viagra had on their erections and sexual activity.

• Viagra is slightly more effective at higher doses.

• Viagra is most effective in mild and moderate ED: Severe ED may be less likely to respond to Viagra.

• Viagra is effective for ED caused by various factors, including diabetes, spinal cord injuries, and prostate surgery. 

Viagra can only help you achieve an erection if you are sexually aroused. It won’t work if you’re not experiencing sexual arousal. 

Viagra is not a cure for ED, as the medication wears off within a few hours. 

How long does Viagra last

How long does Viagra take to work?

Your body rapidly absorbs Viagra into the blood, and it usually works within an hour. However, it can take between 30 minutes and 4 hours to have an effect. 

You should take Viagra before sexual activity as needed. Doctors do not recommend taking Viagra more than once a day. 

Can you make Viagra work faster?

Viagra may work faster when you take it on an empty stomach. 

If you eat before taking Viagra, avoid a high-fat meal if you want the drug to work faster. Fat can slow down the absorption of Viagra into your bloodstream by an hour. 

How long will it stay in your system?

After taking a 100mg dose, Viagra stays in the bloodstream for up to 18 hours after taking the medication. After 4–5 hours, only very small amounts are detectable. 

After taking Viagra, your erection should not last more than four hours. While Viagra is still in your system, the effect on erections wears off due to the low amounts left in your body. 

Side effects of Viagra

Mild side effects

Most side effects of Viagra are mild and temporary. 

The most common side effects may include, but are not limited to: 

Aches and pains

• Headache

• Muscle aches

• Back pain

Gastrointestinal symptoms

• Upset stomach

• Nausea or vomiting 

• Diarrhea 

Skin effects

• Flushed face

• Rash

• Unusually warm skin 

• Increased skin sensitivity 

Other side effects

• Runny nose

• Dizziness

• Nosebleed

• Difficulty sleeping 

As the dose increases, the risk of experiencing side effects becomes more likely. 

If you experience any side effects, speak with your doctor to see whether you should reduce your dosage. 

One study⁴ of men who took the active ingredient of Viagra, sildenafil, concluded that almost half of the participants experienced at least one adverse effect. Most adverse effects, however, were mild or moderate. 

Another study of 979 men with ED found that 3.8% had adverse effects that required a dosage change or discontinuation of Viagra.

Serious side effects

If you experience any of the following side effects, stop using Viagra and seek medical attention immediately. 

Allergic reaction

Swelling around the face and mouth, tightness in the throat, and difficulty breathing, are signs of an allergic reaction. This can be life-threatening, so you must seek emergency care. 

Prolonged erection

A prolonged erection that lasts more than 4–6 hours may be due to a condition called priapism. This damages the penile tissue and can lead to permanent loss of erectile function. 

Vision loss

Blurred vision or the sudden loss of vision in one or both eyes may suggest a condition called non-arteritic anterior ischemic optic neuropathy (NAION), which damages nerves in the eye. 

Hearing loss

Studies have associated Viagra with hearing loss or reduction and tinnitus (ringing or buzzing in the ears).

Heart problems

Chest pain, an irregular heartbeat, or a heart attack may occur when using Viagra. Although rare, they’re more common if you have pre-existing heart disease. 

Bleeding 

Some people may experience bleeding in the brain or lungs. 

Seizures

Seizures are a rare but serious side effect of taking Viagra. 

Precautions when taking Viagra

When taking Viagra, there are some precautions to be aware of.

Determining the correct dose

Viagra comes in doses of 25mg, 50mg, or 100mg. For most people, 50mg is recommended. 

Your correct dose will depend on your age, underlying medical conditions (such as liver and kidney problems), and any other medications you’re currently taking. Always follow the dosage advice given by your doctor. 

Studies on Viagra in older adults are less extensive. Researchers believe a low dose of 25mg is best suited for people over 65. This is because it takes them longer to clear Viagra from their system due to a slower metabolism.

Underlying medical conditions 

If you have certain underlying medical conditions, it may not be safe for you to take Viagra, or you may need to use caution when taking it.  

Let your doctor know if you have any underlying medical conditions, but the following are particularly important: 

Heart conditions 

Viagra may not be suitable for you if you have:

• An irregular heartbeat

• Chest pain

• Heart failure

• Had a heart attack

• Had heart surgery recently

High or low blood pressure

If you have high or low blood pressure or are highly sensitive to blood pressure changes, Viagra may not be appropriate. This is because Viagra lowers your blood pressure, which can worsen a pre-existing issue. 

Eye conditions

If you have the genetic eye condition retinitis pigmentosa, Viagra may not be safe for you. It may increase your risk of experiencing severe eye-related side effects. 

History of priapism

If you’re predisposed to priapism or have ever had an erection that was painful or lasted more than four hours, make sure your doctor is aware. 

Blood or bleeding disorders 

If you have any bleeding disorders or problems with your blood cells, including sickle cell anemia or leukemia, you might be at an increased risk of negative side effects. 

Liver or kidney problems

If you have impaired liver or kidney function, you may require a lower dose of Viagra. It may be harder for your body to clear Viagra from your system safely. 

Anatomical deformation of the penis

Use Viagra with caution if you have any physical deformations of the penis, such as Peyronie's Disease, angulation, or cavernosal fibrosis. 

History of strokes

If you’ve had a stroke in the past six months, use Viagra with caution and follow your doctor’s advice. 

Stomach ulcers

Research has not determined the safety of Viagra in those with stomach ulcers. 

Other considerations

Some experts advise avoiding grapefruit or grapefruit products when using Viagra. This is because grapefruit can increase the amount of Viagra in your blood. An increased amount could raise your risk of experiencing negative side effects. 

Lifestyle factors such as smoking, drug use, and drinking alcohol may increase the risk of severe side effects or influence the effectiveness of Viagra. 

Seek medical attention if you take too much Viagra. 

Drug interactions with Viagra

Some drugs can interact with Viagra. They can negatively impact how it works and your overall health. 

If you take any of the following medications, let your doctor know before starting Viagra:

Blood pressure drugs

These include alpha-blockers and guanylate cyclase stimulators: When taken with Viagra, your blood pressure may drop to dangerously low levels, causing dizziness and fainting. If you take blood pressure medications, your doctor may prescribe you a lower dose of Viagra. 

Nitrate drugs

These include medications for chest pain, which can also lower your blood pressure, and some street drugs, like poppers. 

Other sildenafil drugs

Other medications that contain the active ingredient sildenafil, such as Revatio. Doctors commonly prescribe these for pulmonary arterial hypertension. 

Other drugs

• HIV medications, such as Ritonavir

• Other ED medications, such as alprostadil, Cialis, and Levitra

• Some antibiotics, such as erythromycin

• Some antifungals, such as ketoconazole 

When to see a doctor

Viagra is a prescription drug, so you will need to see your doctor before obtaining it to make sure it will be safe for your circumstances. You should only purchase it online through a registered pharmacy when you have a prescription. 

2013 research found that up to 77%⁵ of Viagra purchased online was fake. Buying fake drugs to avoid the embarrassment you may feel speaking to your doctor isn’t worth the risk to your health. Your doctor has seen ED many times: It’s estimated that ED affects half of all men during their lifetime at any age. Doctors treat without judgment. 

See a doctor if you think you have ED. Several underlying medical causes — such as type 2 diabetes, high blood pressure, and penile injuries — may need treatment before they worsen. 

Once you’ve started Viagra, you might need to see your doctor again. If you want to reduce the dose or think you need a higher dose, always check with your doctor first. 

Remember, not everyone has success with Viagra. Other medications and treatments are available if Viagra doesn’t help you get and maintain erections. 

The lowdown

Viagra is a safe and effective medication for the treatment of ED. Although it is not a cure, it can help you regain erectile function for an enjoyable sex life. 

If you’re wondering if Viagra is suitable for you, speak with your doctor to find out.