What Does Sildenafil Do?

Sildenafil is a medication classified as a phosphodiesterase type 5 (PDE5) inhibitor – meaning that it inhibits the enzyme that causes blood vessels to contract. It is used for erectile dysfunction patients under the brand name of Viagra, in a high dose, and for those suffering with pulmonary arterial hypertension under the name Revatio, in a smaller dose. This article will explain how this PDE5 inhibitor works for each condition.


Sildenafil & Erectile Dysfunction (ED)


Sildenafil inhibits PDE5 from acting on the substance Cyclic Guanosine Monophosphate (Cyclic GMP). PDE5 breaks down Cyclic GMP, which has the usual effect of widening blood vessels and arteries. When broken down, the substance cannot act on blood vessels, meaning that they stay contracted, increasing blood pressure and making it more difficult for blood to access certain parts of the body.

This is a main cause of erectile dysfunction. Even when a man feels sexually aroused, his blood vessels are prevented from widening and letting in more blood flow, meaning he cannot achieve an erection. Taking Sildenafil helps this by inhibiting PDE5, which allows Cyclic GMP to widen the blood vessels to the penis and to cause an erection.

It’s important to dispel the myth that Sildenafil (or Viagra) will cause an erection without sexual stimulation. Sildenafil will only cause a man to get an erection if he is stimulated.

For ED patients, generic Sildenafil or branded Viagra is prescribed in a variety of doses – usually 25mg, 50mg, or 100mg. It is always a larger dose for ED patients than those prescribed Sildenafil for PAH. Your doctor will be able to advise which dose is right for you.

Do not take Sildenafil or its variants without a doctor’s recommendation. Guessing your dose can cause serious complications. If a patient sustains an erection for over 4 hours, he can permanently damage his penis. To prevent unwanted side effects and conditions, tablets should always be taken after the patient has obtained a doctor’s advice and has read the packet directions.

Sildenafil & Pulmonary Arterial Hypertension (PAH)


Sildenafil is used primarily to delay the worsening of PAH in patients, and to help them increase physical activity with less pain and difficulty. It is prescribed at a lesser dose for PAH patients than for ED. Revatio apparently comes in two forms – a 20mg dose in a white round pill, so as not to be mistaken for Viagra, or it can be supplied as a 10mg single-use injection.

For PAH patients, Sildenafil works by decreasing the effectivity of PDE5, meaning that more Cyclic GMP reaches the blood vessels in the lungs to relax and widen them, lessening the tension. This works to decrease the blood pressure to the heart, helping it function, and to reduce pressure in the lungs, helping the patient be more active. Studies show that this significantly helps patients.

Sildenafil can be obtained from a consultation with a doctor either in person or online. Never buy drugs online that do not require a consultation from an accredited doctor.

About Maryam BenhamDr Maryam Benham obtained her medical degree in medicine in Iran in October 2004 and moved to the UK in 2006 and has held full registration with the General Medical Council since 2007. Maryam finished her foundation training at Ealing hospital and has done two years of surgery in different London hospitals such as Royal Free Hospital before deciding to pursue specialist training in General Practice at Kent, Surrey and Sussex (KSS) Deanery in 2011. Since finishing her GP training in September 2014 Maryam has been a dedicated General Practitioner in London.

With special interest in Dermatology, Aesthetics and minor skin procedures alongside her NHS work as a general practitioner, Maryam stays updated in her areas of interest through attending seminars and minor surgery and aesthetic courses. As part of the new generation of highly dedicated and skilled British doctors, Maryam believes that her main aim is to deliver the best care to her patients and to provide them with the best possible medical advice.
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