Does sildenafil cause headaches? Yes, headaches are one of the most frequently reported side effects of sildenafil, a phosphodiesterase type 5 (PDE5) inhibitor commonly prescribed for erectile dysfunction. The medication works by widening blood vessels throughout the body, including those in the brain, which can trigger headaches in many users. Classified as a 'very common' side effect by the MHRA, headaches affect more than 1 in 10 people taking sildenafil. Understanding why this occurs, how to manage it, and when to seek medical advice can help you use this medication safely and effectively.

Does Sildenafil Cause Headaches?

Yes, sildenafil can cause headaches, and this is one of the most frequently reported side effects of the medication. Sildenafil, commonly known by the brand name Viagra, belongs to a class of medicines called phosphodiesterase type 5 (PDE5) inhibitors. It is primarily prescribed for erectile dysfunction and, in some cases, pulmonary arterial hypertension (under a different brand name and dosing regimen, Revatio).

The mechanism by which sildenafil causes headaches is directly related to its pharmacological action. Sildenafil works by inhibiting the PDE5 enzyme, which leads to increased levels of cyclic guanosine monophosphate (cGMP) in smooth muscle cells. This causes vasodilation—the widening of blood vessels—not only in the intended target areas but throughout the body, including the blood vessels in the brain and surrounding tissues. This widespread vasodilation can trigger headaches, which are typically vasodilatory or migraine-like in nature.

The headaches associated with sildenafil typically occur shortly after taking the medication, often within one to two hours when plasma concentrations peak. They are generally mild to moderate in intensity and often improve within several hours but can last longer in some people. The vasodilatory effect is dose-dependent, meaning higher doses of sildenafil are more likely to produce headaches and other vascular side effects such as facial flushing.

It is important to note that whilst headaches are a recognised and common adverse effect of sildenafil, they do not indicate a serious underlying problem in most cases. However, understanding this side effect can help patients make informed decisions about their treatment and manage expectations when starting therapy.

For erectile dysfunction, do not take more than one dose of sildenafil in 24 hours.

How Common Are Headaches with Sildenafil?

Headaches are amongst the most prevalent side effects reported with sildenafil. According to the Medicines and Healthcare products Regulatory Agency (MHRA), headaches are classified as a 'very common' side effect, affecting more than 1 in 10 people who take sildenafil.

The frequency of headaches shows a dose-response relationship. Clinical studies indicate that higher doses are associated with a greater likelihood of experiencing headaches:

• Lower doses: Fewer patients experience headaches

• Higher doses: More patients report headaches

These figures are significantly higher than placebo rates, confirming that sildenafil is indeed the causative agent. The Summary of Product Characteristics (SmPC) for sildenafil consistently lists headache as the most common adverse reaction.

Some patients find that headaches may become less troublesome with continued use of the medication. This may occur as the body adjusts to the effects of sildenafil, though individual experiences vary considerably.

It is worth noting that individual susceptibility varies. Some patients may be more prone to sildenafil-induced headaches due to various factors such as pre-existing headache conditions, concurrent medications, or underlying cardiovascular conditions. Conversely, many patients take sildenafil regularly without experiencing headaches, highlighting the variability in individual responses to the medication.

Managing and Preventing Sildenafil-Related Headaches

For patients who experience headaches with sildenafil, several practical strategies can help manage and potentially prevent this side effect whilst maintaining the therapeutic benefits of the medication.

Dose adjustment is often the first-line approach. If headaches are troublesome, speak with your GP or prescribing clinician about reducing the dose. Many patients find that a lower dose (such as 25 mg or 50 mg instead of 100 mg) provides adequate therapeutic effect with fewer side effects. The Summary of Product Characteristics (SmPC) and British National Formulary (BNF) support individualised dosing based on efficacy and tolerability.

Timing and hydration can make a difference. Taking sildenafil with a full glass of water and ensuring adequate hydration throughout the day may help reduce headache intensity. Dehydration can exacerbate headaches, so maintaining good fluid intake is advisable. High-fat meals can delay the absorption of sildenafil, which may affect its onset of action.

Simple analgesia is generally effective for managing sildenafil-related headaches. Paracetamol (500–1000 mg) is usually the first choice and can be taken as needed when headaches occur. Non-steroidal anti-inflammatory drugs (NSAIDs) such as ibuprofen may also be used if appropriate for you, considering individual risk factors for gastrointestinal, renal, or cardiovascular effects. Speak with your pharmacist or GP about the most suitable pain relief option for your circumstances.

Lifestyle modifications can support headache prevention:

• Limit alcohol when taking sildenafil, as alcohol also causes vasodilation

• Avoid grapefruit juice, which can increase sildenafil levels in your blood

• Ensure adequate rest and avoid taking the medication when overtired

• Manage stress levels, as tension can compound headache symptoms

Important safety information:

• Do not take sildenafil with nitrate medications (prescribed for angina) or recreational nitrates ('poppers') as this can cause a dangerous drop in blood pressure

• Sildenafil is contraindicated with riociguat (used for pulmonary hypertension)

• Certain medications (including some antibiotics, antifungals, and HIV medications) can increase sildenafil levels—check with your prescriber

• Do not exceed one dose in 24 hours for erectile dysfunction

• Do not combine with other PDE5 inhibitors

If you experience side effects from sildenafil, you can report them through the MHRA Yellow Card Scheme (yellowcard.mhra.gov.uk).

When to Seek Medical Advice About Sildenafil Side Effects

Whilst headaches are a common and generally benign side effect of sildenafil, certain symptoms warrant prompt medical attention. Understanding when to contact your GP or seek emergency care is essential for patient safety.

Contact your GP or prescribing clinician if:

• Headaches are severe, persistent, or significantly impact your quality of life

• Headaches worsen over time rather than improving with continued use

• Simple analgesia (paracetamol or ibuprofen) does not provide adequate relief

• You experience headaches alongside other concerning symptoms such as visual disturbances, dizziness, or chest discomfort

• You have a history of migraine and notice a change in your usual headache pattern

Seek immediate medical attention (call 999 or attend A&E) if you experience:

• Sudden, severe headache (often described as 'thunderclap' or the worst headache of your life), which could indicate a serious vascular event

• Chest pain or pressure, particularly if accompanied by shortness of breath, nausea, or pain radiating to the arm or jaw—these may indicate cardiac issues

• Sudden vision loss or significant visual changes in one or both eyes—stop taking sildenafil immediately and seek emergency care

• Sudden hearing loss, tinnitus, or dizziness with hearing changes—stop taking sildenafil and seek urgent medical attention

• Priapism (an erection lasting more than 4 hours), which requires emergency treatment to prevent permanent damage

• Severe allergic reactions, including difficulty breathing, facial swelling, or widespread rash

It is also important to review your medication regimen with your healthcare provider. Sildenafil can interact with numerous medications, particularly nitrates (used for angina), which can cause dangerous drops in blood pressure. If you need emergency treatment, inform healthcare professionals if you have recently taken sildenafil. Alpha-blockers, certain antihypertensives, and other medications may also interact with sildenafil, potentially contributing to side effects including headaches.

If headaches or other side effects make sildenafil unsuitable for you, discuss alternative treatments with your GP. Other PDE5 inhibitors (such as tadalafil or vardenafil) have different pharmacokinetic profiles and may be better tolerated. Your healthcare provider can help identify the most appropriate treatment option based on your individual circumstances, medical history, and treatment goals.

Frequently Asked Questions