Does Viagra Really Affect Male Fertility? What Science Suggests

Millions of guys across the globe pop pills known as sildenafil (brand name Viagra) to treat erectile dysfunction. Viagra is one of the most widely prescribed drugs worldwide. It’s been around for over two decades, since 1998. But we keep seeing questions about whether Viagra impacts fertility in men.

Does Viagra Lower Male Fertility? Short answer: most likely not, according to current research. But there are some details you should know about if you’re currently trying to conceive, or undergoing fertility treatments. Let’s dive in. 

What Is Viagra and How Does It Work?

Viagra (also known by its generic name, sildenafil citrate) is a drug from a group known as phosphodiesterase type 5 (PDE5) inhibitors. It blocks PDE5, which is responsible for the degradation of cyclic guanosine monophosphate, also known as cGMP. By blocking that enzyme, sildenafil lets blood vessels in the penis relax and expand, which allows for and maintains an erection to occur.

At a specialized Male Fertility Clinic, experts often explain that PDE5 is not limited to penile tissue. It is also present in sperm cells. This means sildenafil does not act only on erectile function. It may interact with sperm at a cellular level.

The important question is whether this interaction improves, harms, or has no significant effect on male fertility.

What Does Research Say About the Viagra Effect on Male Fertility?

Sperm Count, Motility, and Morphology: The Reassuring Evidence

The most frequently studied fertility markers are sperm count (how many sperm), motility (how well they swim), and morphology (their shape). These are the three pillars of a standard semen analysis.

Multiple clinical studies have found no harmful effect from standard therapeutic doses of sildenafil on any of these three markers. In a double-blind, placebo-controlled crossover study published in Human Reproduction, 20 healthy male volunteers who took 100 mg of sildenafil showed no significant changes in sperm number, progressive motility, or the proportion of abnormally shaped sperm compared to those who took a placebo.

A separate randomised study from Pfizer, which is reflected in the drug's official prescribing information, stated clearly that single 100 mg oral doses produced no effect on sperm motility or morphology in healthy volunteers.

A 2021 Korean study published in Investigative and Clinical Urology examined 32 men and exposed their sperm samples in the laboratory to concentrations matching the peak semen levels after a standard oral dose. The outcome: no statistically meaningful differences in sperm motility or function compared to the control group.

That said, most of these studies are relatively short-term and involve small numbers of participants. We still have limited data on long-term use across a full spermatogenic cycle, the process by which new sperm develop, which takes around 74 days in humans.

The Acrosome Reaction: A More Complicated Picture

This is where things get a bit more layered. A study published in Fertility and Sterility by researchers at Queen's University Belfast examined 57 male patients attending an assisted reproductive technology unit. They found something unexpected: while sildenafil significantly increased both the number and speed of progressively motile sperm, it also triggered a premature acrosome reaction in a notable proportion of sperm.

Here is why that matters. The acrosome is a cap-like structure on the head of the sperm that contains enzymes. These enzymes are released at exactly the right moment when sperm approaches an egg so the sperm can break through and fertilise it. If the acrosome reaction happens too early, the sperm loses that ability. The Belfast study found acrosome-reacted sperm increased to 22.1% in the better-quality sperm fraction and 16.6% in the lower-quality fraction, compared to 11.8% and 9.4% in the control groups respectively.

This finding raised legitimate questions. If sildenafil makes sperm swim faster but depletes their fertilisation ability before they even reach the egg, that could be a problem especially in an IVF or ICSI setting where timing and sperm function are tightly controlled.

Not every study agrees, though. The 2021 Investigative and Clinical Urology paper mentioned above found no significant difference in the acrosome reaction after two hours of drug exposure. And a 2004 study published in Fertility and Sterility by du Plessis and colleagues found that sildenafil actually increased sperm binding to the egg's outer layer (the zona pellucida), which would suggest a potential benefit rather than harm.

So the acrosome picture remains contested. Lab studies do not always translate directly into real-world pregnancy outcomes, and the concentrations used in some lab studies exceed what sperm would realistically encounter after a standard oral dose.

Read More: Can Human Papillomavirus Affect Male Fertility?

Could Viagra Actually Help Male Fertility in Some Cases?

Okay, there are hints that sildenafil may help indirectly in certain situations.

Guys who have difficulty providing a semen specimen when needed (a common problem with IVF and other assisted reproduction procedures) sometimes take sildenafil for performance issues related to anxiety and stress. Here, the drug could have a fertility aiding effect because it indirectly allows the sperm sample to be collected.

Researchers analyzing one study posted to PubMed reported that Viagra may improve sperm motility as well as sperm-egg binding. This conclusion came with the suggestion that Viagra may help during fertility treatment. What's more, research into erectile dysfunction has found that erectile dysfunction and infertility can be caused by the same underlying issues (diabetes, hormone problems, and heart disease). Treating ED successfully can open the door to attempting natural conception at the optimal time during your partner's cycle.

However, and please note this, sildenafil has not been shown to increase pregnancy rates or rates of live birth. Any benefit would be a byproduct of sexual intercourse.

What Gaps Remain in the Research?

The honest answer is that we do not yet have definitive, long-term clinical data on Viagra's effect on male fertility. Here is what the evidence is still missing:

• Long-term studies: Most research covers single doses or very short treatment periods. A full spermatogenic cycle takes approximately 74 days, and we have little data on what happens to sperm quality over repeated doses across that time frame.

• Larger sample sizes: Many studies involve fewer than 60 participants, which limits how confidently we can generalise findings.

• Real-world IVF outcomes: Lab findings on acrosome reaction and sperm function do not automatically tell us what happens to live birth rates in couples using sildenafil during fertility treatment.

• High-dose or daily use: Most safety data applies to on-demand use at standard doses (25–100 mg). Daily or higher-dose regimens may carry different implications that are not yet well studied.

  
  

Practical Advice: What Should Men Do?

For couples trying to conceive without intervention, the news is reassuring overall. Clinical data at normal doses and with on-demand use have not shown sildenafil to have permanent detrimental effects on sperm count, morphology, or motility.. If you or your partner undergoing assisted reproduction such as IVF, IUI or ICSI cycles, you should mention sildenafil use to your clinical team. Your doctor may decide that due to the concerns around premature acrosome reaction in vitro, they would prefer to manage erectile dysfunction away from your treatment cycle using an alternative strategy.

At myGynaePlus we work with couples at all stages of their fertility journey. Some of these couples have contributing factors to sub fertility from both the male and female members. Although myGynaePlus is a women’s health and Gynaecology clinic, we understand fertility can be an issue affecting both partners. Our team will be able to guide you on where to go next and who to see.

When Should You Speak to a Doctor?

See a GP or fertility specialist if:

• You have been trying to conceive for 12 months without success (or 6 months if you or your partner are over 35)

• You have a known diagnosis of erectile dysfunction alongside fertility concerns

• You are about to start or are currently undergoing assisted reproduction and are using sildenafil

• You have underlying health conditions such as diabetes or hormonal issues that could affect both erection function and sperm quality

A semen analysis is a straightforward starting point. It will give you a clear read on sperm count, motility, and morphology, and from there a specialist can advise whether medication use including sildenafil warrants any adjustments.

Key Takeaways: Viagra and Sperm Health

To put it plainly, here is the current state of the evidence on Viagra's effect on male fertility:

• Sperm count, motility, and morphology: Standard doses of sildenafil do not appear to cause significant harm to these parameters in healthy men.

• Acrosome reaction: Some lab studies suggest premature activation is possible, which could theoretically reduce fertilisation ability but this finding is not consistent across all research.

• Fertility treatments: If you are using sildenafil during IVF or ICSI, inform your clinical team so they can factor this into your care.

• Long-term data: Currently limited. On-demand use at standard doses appears safe; daily high-dose use is less studied.

• Birth defects: No established link has been found between paternal sildenafil use and increased risk of birth defects.

  
  

Book an Appointment

Frequently Asked Questions

Q1: Can I take Viagra while trying to conceive? 

The current evidence suggests on-demand use of sildenafil at standard therapeutic doses does not harm sperm count, motility, or morphology in most healthy men. If you have specific fertility concerns, it is worth discussing with your GP before continuing use.

Q2: Does Viagra reduce sperm count? 

Multiple clinical studies, including randomised controlled trials, have found no significant reduction in sperm count after single doses of 100 mg sildenafil in healthy volunteers. Long-term effects across repeated cycles are less well studied, so daily use warrants a conversation with a doctor.

Q3: Can Viagra affect sperm DNA or cause birth defects? 

There is currently no established evidence linking paternal sildenafil use to increased rates of birth defects or sperm DNA damage at standard therapeutic doses. Animal studies using daily dosing showed no impairment of fertility, but human long-term data remains limited.

Q4: Should I stop taking Viagra before IVF treatment? 

Some research suggests sildenafil may trigger a premature acrosome reaction in sperm under certain lab conditions, which could theoretically affect fertilisation. If you are about to undergo IVF or ICSI, let your fertility team know you use sildenafil so they can advise you appropriately.

Q5: Can Viagra help with fertility if erectile dysfunction is the problem? 

If erectile dysfunction is preventing natural conception attempts, sildenafil may help indirectly by enabling intercourse at fertile times. However, the drug has not been shown to directly improve sperm quality or increase pregnancy rates beyond enabling sex itself.