Why does Viagra cause a headache?

You have finished the candlelight dinner, being careful to avoid a high-fat meal, as you know this will delay the onset of Viagra. You pop the magic blue pill in anticipation of a night of romance, but instead, a headache ruins the evening, and for once, it’s not your wife who has it. One of the most frequent side effects men encounter when taking Viagra is headaches; it is thought that they affect up to 25% of men taking Viagra [1]. In this blog, you will learn why does Viagra cause a headache.

Before we explore why these Viagra-induced headaches occur, we will brush up on the basics. If you already know these facts, you can jump to the appropriate section using the navigation table below.

What is erectile dysfunction?

Erectile dysfunction (ED) is when a man has difficulty getting or keeping an erection firm enough for satisfying sexual activity [2]. While a one-off issue isn’t a big concern, ongoing ED is usually identified when these difficulties persist for around six months. Erectile dysfunction becomes more common as men age, but it can affect anyone, especially if certain health issues are involved [3].

In some cases, erectile dysfunction can signal other health issues, such as heart disease, diabetes, high cholesterol, or high blood pressure [4]. Many cases of ED are related to problems with blood flow, nerve function, hormone levels, or the health of the blood vessels themselves. For instance, endothelial dysfunction—a problem with the inner lining of blood vessels—is often seen in men with erectile dysfunction and can be an early indicator of cardiovascular health concerns [5]. Recognising and addressing ED could be a proactive step in managing overall health risks since researchers now believe that erectile dysfunction is the thin edge of the wedge, heralding the onset of more serious cardiovascular consequences within three years [6].

Another possible factor in erectile dysfunction is low testosterone, a hormone crucial to sexual health and overall vitality. Low testosterone levels can manifest as erectile dysfunction, and a simple blood test can determine if hormone levels might be contributing to ED symptoms [7].

Low testosterone is treatable, and knowing your levels can help determine your best course of action. Whether it’s lifestyle adjustments, medication, or hormone therapy, Medical Mojo provides private consultations and support to help you explore safe and effective treatment options. For more information or to discuss treatment options, contact us or visit our website, medicalmojo.co.uk.

What is Viagra or sildenafil?

Viagra, often referred to as the “little blue pill,” is a medication primarily used to treat erectile dysfunction (ED). It belongs to a class of drugs known as phosphodiesterase type 5 or PDE5 inhibitors, which also include:

• Cialis (Tadalafil)
• Spedra (Avanafil)
• Levitra (Vardenafil)

These medications work by relaxing the blood vessels in your penis, allowing more blood to flow into it to cause an erection.

How does Viagra work?

Viagra, also known as sildenafil, is a medication designed to help men with erectile dysfunction (ED) achieve and maintain an erection by enhancing blood flow to the penis. It belongs to a group of drugs called PDE5 inhibitors (phosphodiesterase type 5 inhibitors), which work by boosting levels of a chemical called cGMP [8]. Think of cGMP as a signal that opens the “floodgates” for blood flow to the penis. Once these gates are open, blood rushes in, increasing pressure and creating an erection.

But how does Viagra fit into this process? Normally, an enzyme called PDE5 can limit cGMP levels, reducing blood flow and making it challenging to get an erection. Viagra temporarily blocks PDE5, increasing cGMP levels and enabling better blood flow [9]. However, it’s important to note that sexual arousal is still needed for Viagra to work; the medication supports the natural process by making it easier for blood to reach the tissues that need it.

What are the side effects associated with Viagra?

In addition to the headaches, several side effects have been identified with Viagra use. The most common adverse reactions observed were:

• flushing (30.8%),
• headache (25. 4%),
• nasal congestion (18.7%), 
• heartburn (10.5%).

All these side effects of Viagra were mild and short-lived [10].

Why does Viagra cause a headache?

What causes a headache? The prevailing idea regarding the pathophysiology of headaches is that they are caused by increased blood flow or vasodilation in the brain. With regards to Viagra and the other PDE5 inhibitors, such as tadalafil or Cialis, they work by increasing blood to the penis by blocking PDE5 enzymes in the penile blood vessels. However, although the PDE5 enzyme is predominantly expressed in the penis, many other organs express the PDE5 enzyme, such as the lungs, heart, nervous system and the brain [11]. So, it was a relatively small intuitive leap to make to infer that Viagra causes headaches by vasodilation or increased blood flow to the brain. But this is not the whole picture.

Does Viagra cause a headache by increased blood flow to the brain?

Do you suffer from migraines? Does Viagra trigger a migraine attack for you? Why am I talking about migraines? Well, it is to provide evidence that Viagra-induced migraines or headaches are caused by vasodilation. If you have ever had a migraine, then the chances are that you have taken some form of “triptan”, such as sumatriptan or Imigran, to provide relief from these headaches. The way that triptans such as sumatriptan work is that they behave as vasoconstrictors to decrease the blood flow to the brain [12]. So, it seems like an open-and-shut case that Viagra causes headaches by increasing blood flow to the brain. Like many other blog writers, I could stop there and be happy to churn out volume over quality…..but I kept digging and have discovered that the way Viagra causes a headache is not as simplistic as vasodilation. So, the answer to the question, does vasodilation cause headaches when you take Viagra, is both yes and no.

The evidence against vasodilation as a cause for Viagra-induced headaches

The doubts regarding vasodilation as the root cause of Viagra-induced headaches started when investigations using ultrasonography failed to reveal any effect of sildenafil on dilating the arteries of the brain [13]. So, the ability of Viagra or sildenafil to cause a headache was attributed to non-vascular mechanisms [14], which we will turn to in the next section.

But before we consign the vasodilatory cause of Viagra-induced headaches to the dustbin of failed scientific theories, let’s take one last look at some more recent research.

One problem with science is that theories can only reflect the technology available at that particular point in time. For example, if more sophisticated methods were available to measure the changes to the blood flow in the brain after taking Viagra, would this demonstrate that vasodilation is indeed a cause of these headaches?

That is what exactly happened when researchers used advanced 3 Tesla magnetic resonance angiography to demonstrate dilation of meningeal and cerebral arteries after sildenafil administration in both healthy individuals and patients with migraine. This new technology was able to detect very subtle changes in the vessels and subsequently found that sildenafil, the generic version of Viagra, did indeed cause vasodilation in the arteries of the brain [15], [16].

The cause of migraines

These discussions over the cause of Viagra-induced headaches have not just occurred among researchers investigating the side effects of sildenafil. These discussions on the causes of headaches have been hotly contested among scientists trying to pinpoint the cause of migraines.

Over the last 300 years, two main ideas have shaped the understanding of migraines: the vascular theory, which suggests migraines are linked to blood vessel changes, and the central neuronal theory, which focuses on brain circuits.

Treatments like ergotamine and triptans, which constrict blood vessels, initially supported the vascular theory. However, recent research shows that blood vessel dilation alone doesn’t fully explain migraines. This shift has led scientists to explore the role of key brain circuits, including the trigeminal ganglia, brainstem regions, hypothalamus, and thalamus, which are involved in processing sensory signals from the head. If you are having trouble picturing all these areas of the brain and what they do, look at our “How the brain works TikTok video”, which describes the important role that the thalamus plays as the brain’s information-processing centre.

Migraines are caused by an imbalance in brain circuits

Current evidence suggests that migraines are likely due to imbalances in these brain circuits, particularly those controlling sensory activity related to head pain. One key player is the neurotransmitter calcitonin gene-related peptide (CGRP), found in neurons within the trigeminal ganglion.

CGRP is released during migraine episodes and can trigger symptoms in individuals prone to migraines. Drugs, such as Vydura that block CGRP receptors can effectively halt migraines, indicating a strong link between CGRP and migraine pathways.

Additionally, triptans, traditionally thought to work by narrowing blood vessels, may also impact the neuronal circuits directly involved in migraines, suggesting a dual mechanism beyond vascular effects [17].

This emerging view highlights that while blood vessel changes may play a role, the root cause of migraines likely lies within the brain’s neuronal pathways, offering new directions for more targeted migraine treatments.

What other mechanisms are responsible for the Viagra-induced headache?

Now, let’s head back to discussing the Viagra-induced headaches.

Studies investigating the cause of migraine have identified two independent pain signalling pathways that converge [17]. These two pathways are :

• cAMP-dependent pathway
• cGMP-dependent pathway

The researchers reasoned that a migraine attack could be caused by either of these two intracellular signalling pathways.

Researchers have shown that blocking PDE-5 can trigger migraine attacks in individuals who have migraines, even if they’ve been pre-treated with a CGRP (calcitonin gene-related peptide) blocking antibody. This suggests that migraine attacks can be activated by pathways linked to cGMP (cyclic guanosine monophosphate) signalling, independent of CGRP receptor activity. This finding aligns with past studies showing that CGRP blockers couldn’t prevent migraines caused by a nitric oxide (NO) donor, highlighting that multiple pathways may contribute to triggering migraine symptoms [18].

Therefore, it seems likely that migraines can be triggered by two separate cellular pathways: one that relies on cAMP (cyclic adenosine monophosphate) and another on cGMP (cyclic guanosine monophosphate). These pathways work independently, each capable of initiating a migraine attack on its own.

Proposed site(s) and mechanisms of action for Viagra-induced headache

So, we could have ended the blog early simply by saying that this side effect resulted from vasodilation, and then I could go on and enjoy the rest of my Sunday. Yes, I am writing this article on a Sunday. But at Medical Mojo, we want to give you the most up-to-date research and won’t cut corners. So, here I am in a lovely coffee shop on my second Americano, wondering how I will write the next paragraph.

So, we have already discussed why vasodilation is not the whole story; the latest research suggests that Viagra and other PDE5 inhibitors cause headaches by involvement at both vascular and neuronal sites.

Nitric oxide and vasodilation

We have spoken a lot about cGMP and PDE5 but have not mentioned the real star of the show, nitric oxide or NO; without it, the vasodilation associated with Viagra would not occur. Nitric oxide is the primary activator of the cGMP pathway. Upon its release from the walls of the blood vessels (vascular endothelium), nitric oxide diffuses into the vascular smooth muscle cells, stimulating the release of cGMP [19].

The increased levels of cGMP in the smooth muscle trigger the opening of potassium channels, which then causes vasodilation.

The new proposed model suggests that this nitric oxide-induced pathway sensitises the trigeminal nerves responsible for your headaches [20]. The sensitisation is part chemical, with the potassium efflux and part mechanical via vasodilation. This then triggers the activation of nociceptive (pain-sensing) neurons, resulting in migraine pain [20].

The cGMP pathway, activated by nitric oxide (NO), doesn’t just work on blood flow but also affects the nervous system [21], especially in terms of how nerves respond to pain [22]. In simpler terms, here’s how it can contribute to migraines:

• Pain Signals in Nerves: This pathway can make certain nerve cells in areas like the trigeminal ganglion (a major pain pathway in the face and head) more sensitive to pain by changing ion channel activity.
• Impact on Pain Perception: In the brain, the NO and cGMP pathways help control how we perceive pain and can make the nervous system more responsive to it, a process known as central sensitisation [23].
• Animal Research Insights: Studies in animals suggest that NO can lead to heightened nerve cell excitability in areas associated with headache pathways, such as the spinal trigeminal nucleus [24].

These effects suggest that drugs like Viagra, which influence this pathway, might impact sensory nerves in ways that can trigger or intensify migraines.

Why can sildenafil have effects on the brain?

Viagra or sildenafil is a lipophilic drug or fat-soluble drug, meaning that it can diffuse into fat-rich tissues such as our brains. This helps explain why we get side effects in the brain, such as headaches [25].

Sildenafil and glutamate

Researchers have found that sildenafil administration increases cGMP levels, triggering a transient increase in glutamate concentrations in the brainstem [26]. Why is this significant? Well this is because glutamate is an excitatory neurotransmitter and suggests that it’s increased levels may contribute to the initiation of a migraine attack.

The complex effects of the cGMP pathway in the nerves and blood vessels involved in migraines highlight its important role in migraine development. Future research should focus on understanding the exact ways sildenafil (Viagra) affects pain signalling in these migraine-related pathways to explain its influence on migraine symptoms better.

Summary. How does Viagra cause a headache?

The long and short of it is that it’s not as simple as increased blood flow to the brain. The vasodilation does play a role, but the sensitisation of the nerve fibres by changes in potassium flows also plays a role.

The complex effects of the cGMP pathway in the nerves and blood vessels involved in migraines highlight its important role in migraine development. Future research will increase our understanding of the exact ways sildenafil (Viagra) affects pain signalling in these migraine-related pathways to explain its influence on migraine symptoms better.

The bad news is that after all this writing, and reading, if you are still here, we still cannot be sure of the precise mechanism that triggers these headaches when you take Viagra. The good news is that although we don’t know for sure why Viagra causes headaches, we have an increased understanding. This is great for science because it opens up new areas of research, and eventually, this leads to new drugs being developed. A case in point is Vydura, a calcitonin gene-related peptide antagonist for migraines. If we stuck to the vasodilatory theory of migraines, then this breakthrough drug for migraines would not have been invented.

If you suffer from migraines and find that your existing medicines are not providing pain relief, you can try the Vydura after completing a short questionnaire.

How long do Viagra headaches last?

The headaches associated with Viagra or sildenafil use are usually mild, short-lived and manageable [27]. However, if you were not expecting a headache when taking Viagra, the experience can be off-putting and may prevent you from using it again. That is why we write these incredibly detailed articles so that you know what to expect after taking Viagra or sildenafil and take some pre-emptive measures to reduce these side effects.

Typically, Viagra headaches are not serious. Most mild headaches will resolve on their own within one to three hours. However, some men may experience headaches that persist while the medication is still in their system. Once Viagra is cleared from your body, the headache should subside. Interestingly, many users report that their bodies adapt to the medication over time, leading to fewer and less intense headaches.

Tips to prevent headaches from Viagra, Cialis, or Levitra

Have you ever heard the phrase, “No pleasure without pain”? Well, for those unfortunate to get headaches after taking the little blue pill, this seems to describe Viagra perfectly. However, forewarned is forearmed is another proverb that can describe taking Viagra. Now that you have an understanding of why a headache potentially can occur after taking Viagra, let’s now turn to how you can mitigate this side effect.

1. Consider a lower dose

Sounds intuitive, doesn’t it? But often, the common sense approach to dealing with Viagra’s side effects is the most effective. The likelihood of experiencing headaches usually increases with higher dosages of erectile dysfunction medications.

If you’re currently using a higher dose, like 100mg of Viagra, you might want to try a lower dose, such as 25mg or 50mg. Experiment with the doses to find one that provides you with an erection but without the side effects. If you need any advice regarding changing your dose, please email us at info@medicalmojo.co.uk.

2. Stay Hydrated

Dehydration can make a headache worse, and staying hydrated can actually improve symptoms. A recent study discovered that women who consumed higher amounts of water and overall fluids (approximately 2 litres daily) experienced a decrease in the severity, length, and frequency of migraine attacks. Additionally, these women reported less disability associated with migraine episodes compared to those with lower fluid intake [28].

Remember, tea and coffee are diuretics and can worsen dehydration, so don’t rely on them to keep you hydrated, just to keep you awake. If you want to find out how caffeine is able to do this, watch our TikTok video on “How does caffeine work?”.

3. Consider Alternative erectile dysfunction medications

Another proverb for you is that “a change is as good as rest”. Well, with the issue of Viagra-induced headaches, trying an alternative PDE5 inhibitor may work despite the fact they all have the same mechanism of action. Other common erectile dysfunction tablets include:

• Cialis or tadalafil
• Levitra or vardenafil
• Spedra or avanfil

However, bear in mind that although the different erectile dysfunction drugs all work by blocking the phosphodiesterase type 5 enzyme, they have different pharmacokinetics. Basically, they differ in the way the body deals with them. For example, Cialis has a longer duration of action, which may result in a greater incidence or severity of headaches.

Other options include penile injection preparations such as Caverject and the penile gel Eroxon.

If headaches persist with your current medication, you can discuss other options with us at info@medicalmojo.co.uk.

What to do if you get a Viagra headache?

If you do experience a headache after taking Viagra, here are some effective pain relief methods:

1. Over-the-counter (OTC) pain relievers

If the headache persists or you want some pain relief, you can try over-the-counter pain relief. Just a few points to bear in mind: if you also get heartburn after taking Viagra or sildenafil, then you should avoid ibuprofen or other NSAIDs, which will aggravate the heartburn. Another thing to bear in mind is that painkillers often contain several ingredients to increase their analgesic effects, such as co-codamol, which contains paracetamol and codeine or dihydrocodeine. Although providing powerful pain relief, they can cause drowsiness, so you need to factor this in before your night of passion.

The following is a list of painkillers available from medical mojo.co.uk.

• Paracetamol
• Nurofen Plus
• Solpadeine Plus Soluble
• Paramol tablets

Solpadeine Plus and Solpadeine Max are available as both regular and soluble tablets. The benefit of using soluble tablets is that they get to work faster.

2. Apply a Hot or Cold Compress

A hot or cold compress on your forehead or neck may help ease headache pain—experiment with both to see which provides more relief.

3. Dim the Lights

These will probably already be dimmed; after all, you did take the Viagra for a reason, didn’t you? Bright lights can worsen headache pain. To help you relax, create a soothing environment by dimming lights or using low-screen settings.

4. Drink a Caffeinated Beverage (In Moderation)

A moderate amount of caffeine from coffee or tea can help alleviate headache pain. Just remember to hydrate afterwards, as caffeine is also a diuretic.

Conclusion: Managing Viagra headaches

If you’re starting Viagra, consider beginning with a lower dose (like 50mg) to minimise side effects. If headaches occur, don’t hesitate to discuss options for adjusting your dosage or switching medications with your healthcare provider (Us!). Also, try the strategies outlined above to help with these Viagra-induced headaches.

While headaches can happen, they are often mild and manageable. For most men, the benefits of enjoying a fulfilling sex life with Viagra far outweigh the minor inconvenience of occasional headaches. If you have any concerns or persistent symptoms, please contact us via our email at info@medicalmojo.co.uk.

Seeking support for sexual health with Medical Mojo

If you’re exploring options like Viagra (sildenafil) to improve sexual health, talking to a healthcare provider is an important first step. At MedicalMojo.co.uk, we’re here to provide expert guidance customised to your individual health needs so you can approach treatment options confidently and safely. Addressing personal concerns with a professional can make a real difference in finding the right solutions, and our team is here to support you every step of the way.

Why Medical Mojo is your trusted choice for sexual health support

Are you considering Viagra or other solutions for enhancing sexual health? Having guidance from trusted professionals ensures your treatment is safe and suited to you. Medical Mojo offers private, supportive telehealth services to men dealing with sensitive concerns like erectile dysfunction, with experienced pharmacists, doctors, and therapists on hand to provide clear, informed recommendations.

Here’s why MedicalMojo.co.uk stands out for sexual health support:

• Private, judgment-free consultations from the comfort of your home
• Personalised advice based on your complete health profile
• Health screenings to ensure Viagra is suitable for you
• Ongoing support and follow-up throughout your treatment journey
• Clear expectations on what Viagra can realistically offer
• Holistic lifestyle advice to support and improve sexual health naturally
• Access to reliable, evidence-based resources on all aspects of sexual health
• Tailored health coaching to help you regain confidence and satisfaction
• Custom compounded medicines by our pharmacy experts

With Medical Mojo, you’ll gain a clear understanding of what Viagra can—and can’t—achieve, helping you set realistic expectations and make informed choices. To learn more, feel free to contact info@medicalmojo.co.uk.

Disclaimer: This article is for informational purposes only and is not a substitute for professional medical advice.

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