VIAGRA® (sildenafil citrate)

[79][80] In December 2017, Pfizer released its own generic version of Viagra.

Risk Type	Description	Severity	Probability	Notes
Heart Complications	Increased risk of hypertension, stroke	High	Moderate	Use with caution, especially with existing conditions
Psychological Effects	Anxiety, mood swings, dependence	Moderate	High	Long-term effects are uncertain
Drug Interactions	Harmful interactions with other medications	High	Variable	Must consult healthcare provider
Adverse Reactions	Nausea, dizziness, allergic responses	Low	Variable	Seek immediate medical attention if occurs

As of 2018[update], the US Food and Drug Administration has approved fifteen drug manufacturers to market generic sildenafil in the United States.

Why is this medication prescribed?

Other drugs that operate by the same mechanism include tadalafil (Cialis) and vardenafil (Levitra). Sildenafil is broken down in the liver by hepatic metabolism using cytochrome p450 enzymes, mainly CYP450 3A4 (major route), but also by CYP2C9 (minor route) hepatic isoenzymes. The major product of metabolisation by these enzymes is N-desmethylated sildenafil, which is metabolised further. This metabolite also has an affinity for the PDE receptors, about 40% of that of sildenafil. Thus, the metabolite is responsible for about 20% of sildenafil's action.

Key takeaways

Sildenafil is excreted as metabolites predominantly in the feces (about 80% of administered oral dose) and to a lesser extent in the urine (around 13% of the administered oral dose). If taken with a high-fat meal, absorption is reduced; the time taken to reach the maximum plasma concentration increases by around one hour, and the maximum concentration itself is decreased by nearly one-third. When taken orally, sildenafil for erectile dysfunction results in an average time to onset of erections of 27 minutes fildena 100mg (ranging from 12 to 70 minutes). Sublingual use of sildenafil for erectile dysfunction results in an average onset of action of 15 minutes and lasting for an average of 40 minutes. The preparation steps for synthesis of sildenafil are:[54] Methylation of 3-propylpyrazole-5-carboxylic acid ethyl ester with hot dimethyl sulfate Hydrolysis with aqueous sodium hydroxide (NaOH) to free acid Carboxamide formation with refluxing thionyl chloride/NH4OH Reduction of nitro group to amino group Sildenafil (compound UK-92,480) was synthesized by a group of pharmaceutical chemists led by Simon Campbell[55] working at Pfizer's Sandwich, Kent, research facility in England. Seven of these companies are based in India.

Product	Dosage	Quantity + Bonus	Price
Kamagra Soft Tabs	100mg	180 + 8 Pills	425.45€ 405.19€	Buy
Viagra Generic	200mg	20 Pills	61.69€ 58.75€	Buy
Viagra Oral Jelly	100mg	30 + 5 Sachets	115.76€ 110.25€	Buy
Viagra Professional	100mg	180 + 4 Pills	337.30€ 321.24€	Buy
Levitra Generic	40mg	10 Pills	41.37€ 39.40€	Buy
Cialis Generic	10mg	20 Pills	48.23€ 45.93€	Buy
Cialis Professional	20mg	10 Pills	48.29€ 45.99€	Buy
Viagra Generic	100mg	270 + 10 Pills	270.47€ 257.59€	Buy
Priligy Generic Dapoxetine	60mg	180 + 10 Pills	494.76€ 471.20€	Buy
Viagra Professional	100mg	90 + 2 Pills	207.09€ 197.23€	Buy
Levitra Original	20mg	48 + 4 Pills	235.14€ 223.94€	Buy
Kamagra Effervescent Tablets	100 mg	28 Pills	90.83€ 86.50€	Buy
Cialis Generic	5mg	270 + 10 Pills	205.81€ 196.01€	Buy
Viagra Original	100mg	64 + 4 Pills	264.15€ 251.57€	Buy
Viagra Generic	100mg	20 Pills	45.58€ 43.41€	Buy
Cialis Original	20mg	14 + 2 Pills	95.75€ 91.19€	Buy
Cialis Original	20mg	34 + 2 Pills	183.99€ 175.23€	Buy

The patent for Pfizer's Viagra sildenafil to treat erectile dysfunction expired in April 2020.

My “little blue pill” isn’t blue, it’s white. Is this normal?

Plano, and Diego A. Golombek of Universidad Nacional de Quilmes, Argentina, for their discovery that sildenafil helps treat jet lag recovery in hamsters. Professional athletes have been documented using sildenafil, believing the opening of their blood vessels will enrich their muscles. In turn, they believe it will enhance their performances. Acetildenafil and other synthetic structural analogs of sildenafil which are PDE5 inhibitors have been found as adulterants in a number of "herbal" aphrodisiac products sold over-the-counter.

Lampana Group Co., Ltd. (Secondary Profile)

[41] These analogs have not undergone any of the rigorous testing that drugs like sildenafil have passed, and thus have unknown side-effect profiles. [42] Some attempts have been made to ban these drugs, but progress has been slow so far, as, even in those jurisdictions that have laws targeting designer drugs, the laws are drafted to ban analogs of illegal drugs of abuse, rather than analogs of prescription medicines. However, at least one court case has resulted in a product being taken off the market. The US Food and Drug Administration (FDA) has banned numerous products claiming to be Eurycoma longifolia that, in fact, contain only analogs of sildenafil. [44][45][46] Sellers of such fake herbals typically respond by just changing the names of their products. In 2026 a chocolate syrup called Boner Bears from Lockout Supplements was recalled through the FDA because of it containing Sildenafil as an undisclosed ingredient.

Understanding Sildenafil

It was initially studied for use in hypertension (high blood pressure) and angina pectoris (a symptom of ischaemic heart disease). [56] The first clinical trials were conducted in Morriston Hospital in Swansea. [57] Phase I clinical trials under the direction of Ian Osterloh suggested the drug had little effect on angina, but it could induce marked penile erections. [58][59] Pfizer therefore decided to market it for erectile dysfunction, rather than for angina; this decision became an often-cited example of drug repositioning. [60][61] The drug was patented in 1996, approved for use in erectile dysfunction by the FDA on 27 March 1998, becoming the first oral treatment approved to treat erectile dysfunction in the United States, and offered for sale in the United States later that year.

Taking sildenafil citrate with other drugs like cocaine

[62] It soon became a great success: annual sales of Viagra peaked in 2008 at US$1.934 billion. In the US, even though sildenafil is available only by prescription from a doctor, it was advertised directly to consumers on TV (famously being endorsed by former United States Senator Bob Dole and football star Pelé). Numerous sites on the Internet offer Viagra for sale after an "online consultation", often a simple web questionnaire. Viagra and other products for sexual dysfunction, termed sexuopharmaceuticals, proliferated new types of specialised marketing for such products. [66] Viagra and similar prescription pharmaceuticals were promoted by images in media to the extent of becoming a cultural icon, at the time a relatively new phenomenon known to be permitted only in the United States and New Zealand and which is believed to have significantly contributed to norms regarding male sexuality. Counterfeit Viagra, despite generally being cheaper,[88] can contain harmful substances or substances that affect how Viagra works, such as blue printer ink, amphetamines, metronidazole, boric acid, and rat poison.

Source Type	Typical Availability	Reliability	Price Range (per pill)	Notes
Online Dark Web	High	Low	$20 - $50	Risk of counterfeit
Black Market	Moderate	Low	$15 - $40	Illegal and unsafe
Prescription Pharmacies	Very low	High	$10 - $30 (with prescription)	Legal but strict access
Unregulated Vendors	Variable	Low	$10 - $60	High risk of scams

Viagra is one of the world's most counterfeited medicines.

• Use secure payment methods when purchasing blue pills online.
• Beware of deals that seem too good to be true; they may be scams.
• Search for certifications or approvals from health authorities.
• Avoid buying from unverified social media sellers.
• Consider telemedicine services for online prescriptions.
• Look at shipping restrictions to avoid customs confiscation.
• Track your package until delivery for peace of mind.

[90][91] According to a 2012 Pfizer study, around 80% of sites claiming to sell Viagra were selling counterfeits.

• Know the difference between brand name and generic blue pills.
• Research any ongoing clinical trials involving blue pills.
• Observe the effects after first use and report abnormalities.
• Avoid sharing your buying experience on unsecured forums.
• Discover apps for medication reminders and information.
• Check for any upcoming regulatory changes affecting blue pills.
• Keep emergency contact numbers handy related to drug poisoning.

An October 2023 release stated that erectile dysfunction medicines were the most seized drugs by the Interpol[92] accounting for 22% of seizures.

Country	Legal Status	Purchase Restrictions	Age Limit	Online Purchase Allowed
United States	Illegal without prescription	Prescription required	18+	No
United Kingdom	Controlled substance	Restricted to pharmacies	18+	Yes
Canada	Prescription-only	Only through licensed pharmacies	19+	Limited online options
Australia	Illegal without medical prescription	Prescription required	18+	No
Germany	Prescription enforced	Pharmacies only	18+	Yes

In 1992, Pfizer filed a patent covering the substance sildenafil and its use to treat cardiovascular diseases.

• Check if the blue pill contains any alcohol or stimulants.
• Verify if the blue pill is suitable for your age group.
• Know how to properly dispose of unused or expired pills.
• Identify reputable forums or blogs for buyer tips and experiences.
• Familiarize yourself with common myths and facts about blue pills.
• Monitor temperature and humidity if shipping takes long.
• Ensure the seller provides clear contact information.

[96] This would be marketed as Revatio.

• Look for blue pills that have passed third-party lab testing.
• Confirm the seller’s return policy before completing a purchase.
• Ask about refund procedures in case of damaged or incorrect items.
• Verify the seller’s customer support responsiveness.
• Gather information on the pill’s active ingredient and concentration.
• Check for user testimonials about long-term use outcomes.
• Compare delivery costs to find the most economical option.

The patent was published in 1993 and expired in 2012.

How do you take Viagra?

Sildenafil and/or N-desmethylsildenafil, its major active metabolite, may be quantified in plasma, serum, or whole blood to assess pharmacokinetic status in those receiving the drug therapeutically, to confirm the diagnosis in potential poisoning victims, or to assist in the forensic investigation in a case of fatal overdose. Nitric oxide (NO) in the corpus cavernosum of the penis binds to guanylate cyclase receptors, which results in increased levels of cGMP, leading to smooth muscle relaxation (vasodilation) of the intimal cushions of the helicine arteries. This smooth muscle relaxation leads to vasodilation and increased inflow of blood into the spongy tissue of the penis, causing an erection. [49] Robert F. Furchgott, Ferid Murad, and Louis Ignarro won the Nobel Prize in Physiology or Medicine in 1998 for their independent study of the metabolic pathway of nitric oxide in smooth muscle vasodilation.

Can I buy the generic Viagra or Sildenafil Citrate over the counter?

The molecular mechanism of smooth muscle relaxation involves the enzyme CGMP-dependent protein kinase, also known as PKG. This kinase is activated by cGMP and it phosphorylates multiple targets in the smooth muscle cells, namely myosin light chain phosphatase, RhoA, IP3 receptor, phospholipase C, and others. [50] Overall, this results in a decrease in intracellular calcium and desensitizing proteins to the effects of calcium, engendering smooth muscle relaxation. The molecular structure of sildenafil is similar to that of cGMP and acts as a competitive binding agent of PDE5 in the corpus cavernosum, resulting in more cGMP and increased penile response to sexual stimulation. [49][51] Without sexual stimulation, and therefore lack of activation of the NO/cGMP system, sildenafil should not cause an erection. The patent on Revatio (indicated for pulmonary arterial hypertension rather than erectile dysfunction) expired in late 2012. Generic versions of this low-dose form of sildenafil have been available in the US from a number of manufacturers, including Greenstone, Mylan, and Watson, since early 2013.

Online Sildenafil Prescription

[67] One author notes that although the effect of Viagra is only limited to penile blood vessels, advertisements routinely use imagery of couples hugging, smiling and dancing, with the author claiming that pharmaceutical companies were deceptive in the use of such advertisements. In 2000, Viagra sales accounted for 92% of the global market for prescribed erectile dysfunction pills. [69] By 2007, Viagra's global share had plunged to about 50%[70] due to several factors, including the entry of Cialis and Levitra, along with several counterfeits and clones, and reports of vision loss in people taking PDE5 inhibitors. [71][72] In 2008, the FDA forced Pfizer to remove Viva Cruiser, an advergame for Viagra, from appearing on Forbes, after the game failed to disclose risk information about the drug. In February 2007, it was announced that Boots, the UK pharmacy chain, would try over-the-counter sales of Viagra in stores in Manchester, England.

Is there a difference between Viagra and Sildenafil?

Males between the ages of 30 and 65 would be eligible to buy four tablets after a consultation with a pharmacist. [75] In 2017, the Medicines and Healthcare products Regulatory Agency (MHRA) enacted legislation that expanded this nationwide,[76] allowing a particular branded formulation of Sildenafil, Viagra Connect (50 mg), to be sold over the counter and without a prescription throughout the UK from early 2018. While the sale remains subject to a consultation with a pharmacist, the other restrictions from the trial have been removed, allowing customers over the age of 18 to purchase an unlimited number of pills. In May 2013, Pfizer, which manufactures Viagra, told the Associated Press they will begin selling the drug directly to people on its website. Pfizer's patents on Viagra expired outside the US in 2012; in the US they were set to expire, but Pfizer settled litigation with each of Mylan and Teva which agreed that both companies could introduce generics in the US in December 2017.