Common use of Viagra for erectile dysfunction
Viagra is an oral treatment for erectile dysfunction (ED), defined as persistent difficulty attaining or sustaining an erection sufficient for satisfactory sexual activity. As a PDE5 inhibitor, it supports the body’s normal erectile response by increasing blood flow to the penile tissues during arousal. It does not boost libido or trigger erections on its own—sexual stimulation is still required. When used with appropriate medical advice, Viagra can improve firmness, reliability, and sexual confidence, which may enhance overall quality of life for many men and their partners.
Sildenafil, the active ingredient in Viagra, is also used under other brand names and dosing schedules for conditions such as pulmonary arterial hypertension (PAH). Those indications have different doses, safety profiles, and monitoring needs. This article focuses solely on Viagra for ED in adult men. If you have significant medical conditions, take multiple medicines, or are uncertain whether Viagra is right for you, speak with a registered healthcare professional for advice tailored to your situation.
How Viagra works: PDE5 inhibition and blood flow
Sexual arousal leads to nitric oxide release and formation of cyclic guanosine monophosphate (cGMP), which relaxes smooth muscle in penile arteries and the corpus cavernosum. Viagra selectively blocks phosphodiesterase type 5 (PDE5), the enzyme that breaks down cGMP. By slowing cGMP degradation, Viagra helps maintain smooth muscle relaxation and increases arterial inflow, producing firmer erections when arousal is present. Effects typically begin within 30–60 minutes (often sooner on an empty stomach) and may persist for up to four hours. A high-fat meal can delay onset. Do not take Viagra more than once in any 24-hour period.
Dosage and direction for Viagra
For most adults, the usual starting dose is 50 mg taken as needed about 30–60 minutes before sexual activity. Depending on response and tolerability, a clinician may adjust to 25 mg (for increased sensitivity, older age, or interacting medicines) or up to 100 mg (for inadequate effect). Do not take more than one dose in 24 hours. Swallow tablets with water. Taking Viagra on an empty stomach or avoiding a heavy, high-fat meal can help it work sooner. If you drink alcohol, keep it moderate; excess alcohol can blunt erectile performance and increase dizziness or low blood pressure.
Some people should start at a lower dose. Adults aged 65 years or older, those with notable liver or kidney impairment, and people taking strong CYP3A4 inhibitors (for example, ritonavir or ketoconazole) often begin at 25 mg to reduce side-effect risk. If you use an alpha-blocker for prostate symptoms or blood pressure, your clinician may adjust timing and dosing to reduce symptomatic hypotension. Do not combine Viagra with other PDE5 inhibitors or any nitrate therapy. Follow your prescriber’s instructions closely; do not increase the dose yourself if the first attempt falls short. It may take several supervised trials to identify your optimal dose.
If a dose seems ineffective, consider other factors before changing strength. Allow sufficient time after dosing, ensure adequate sexual stimulation, keep alcohol intake modest, and avoid heavy high-fat meals around dosing. Address modifiable contributors to ED—such as sleep quality, stress, smoking, and control of chronic conditions—since improvements can enhance response to Viagra. If difficulties continue after multiple trials, consult your clinician; you may need a dose change, a different PDE5 inhibitor, or assessment for cardiovascular, endocrine, neurological, or psychological causes.
Precautions before taking Viagra
A medical assessment is advisable before starting Viagra, particularly if you have cardiovascular disease, risk factors for heart attack or stroke, or symptoms like chest pain, breathlessness, or dizziness with exertion. Inform your clinician about any history of low blood pressure, uncontrolled hypertension, severe kidney or liver disease, retinitis pigmentosa, bleeding disorders, active peptic ulcer, anatomical penile curvature (e.g., Peyronie’s disease), or conditions that predispose to priapism (such as sickle cell disease, multiple myeloma, or leukaemia). Use caution with eye or ear conditions; rare cases of sudden vision or hearing loss have been reported—seek urgent medical care if these occur.
Contraindications to Viagra
Do not use Viagra if you take any nitrates (for example, glyceryl trinitrate, isosorbide mononitrate/dinitrate, or recreational “poppers” containing amyl or butyl nitrite), as the combination can cause dangerous hypotension. Viagra is also contraindicated with guanylate cyclase stimulators such as riociguat. Avoid use if you have a known allergy to sildenafil or any tablet component. Viagra is generally not recommended for individuals for whom sexual activity is inadvisable due to unstable cardiovascular status, or after recent serious cardiac events (e.g., myocardial infarction or stroke) until a clinician clears you.
Possible side effects of Viagra
Common, usually mild effects include headache, flushing, dizziness, nasal congestion, dyspepsia (indigestion), and back or muscle aches. Some men notice visual changes—most often a blue-green tinge or increased light sensitivity—which are typically short-lived. Using the lowest effective dose, avoiding heavy alcohol consumption, and spacing doses at least 24 hours apart can improve tolerability. If side effects are troublesome, speak with your clinician about dose changes or alternative PDE5 inhibitors.
Serious but uncommon reactions include marked hypotension, chest pain, prolonged or painful erections (priapism), sudden vision loss consistent with non-arteritic anterior ischaemic optic neuropathy (NAION), and sudden hearing decrease or loss. Seek urgent medical attention if you experience chest pain, fainting, a painful erection lasting more than four hours, one-sided vision changes, or abrupt hearing loss. Allergic reactions (such as rash, swelling, or breathing difficulty) are rare but require immediate care. Report new or worsening symptoms promptly to your healthcare professional.
Drug interactions with Viagra
Nitrates and riociguat are absolute contraindications. Use caution with alpha-blockers (used for benign prostatic hyperplasia or hypertension) and other antihypertensives, which can intensify blood pressure–lowering effects; your clinician may separate dosing or recommend a lower Viagra dose. Strong CYP3A4 inhibitors—including ritonavir, cobicistat, ketoconazole, itraconazole, clarithromycin, and grapefruit products—can increase sildenafil levels and side-effect risk; dose reduction is often necessary. Conversely, CYP3A4 inducers such as rifampicin, carbamazepine, or phenytoin may reduce effectiveness.
Avoid using Viagra alongside other PDE5 inhibitors or ED therapies on the same day. Heavy alcohol intake can worsen dizziness and hypotension and blunt erectile response. Grapefruit juice may raise sildenafil exposure; consider limiting or avoiding it. Always provide your clinician and pharmacist with a complete, current list of all prescription and over-the-counter medicines, supplements, and recreational substances so they can identify clinically relevant interactions before you start Viagra.
Missed dose
Viagra is used on an as-needed basis for sexual activity, so there is no standard “missed dose” routine. If a planned encounter passes and you did not take a tablet, simply wait for the next appropriate occasion. Do not take extra tablets to compensate, and never exceed one dose within 24 hours. Note that sildenafil for pulmonary arterial hypertension follows a different regimen; do not interchange those directions with Viagra for ED without explicit medical advice.
Overdose
Taking more than the prescribed amount can raise the risk of severe headache, dizziness, fainting due to low blood pressure, visual disturbances, priapism, and cardiovascular complications. There is no specific antidote for sildenafil overdose. If you suspect an overdose, seek immediate medical care or contact the Poisons Information Centre on 13 11 26 in Australia. Call 000 for emergencies. Do not drive yourself if you feel light-headed or unwell. Emergency clinicians will provide supportive care and monitoring to manage symptoms and reduce complications.
Storage
Store Viagra tablets at room temperature (around 20–25°C), protected from excessive heat, moisture, and direct light. Keep tablets in the original child-resistant container until use. Avoid storing medicines in bathrooms where humidity is high. Keep out of reach of children and pets. Do not use tablets past the expiry date, and safely discard any damaged or discoloured pills. When travelling, carry your medicine in its labelled container and follow airline and security regulations.
Australian sale and prescription policy: how to buy Viagra without prescription through Geisinger HealthSouth
In Australia, Viagra (sildenafil) is a Schedule 4 (prescription-only) medicine under the national Poisons Standard. Australian federal and state/territory laws require review by an AHPRA-registered clinician to ensure safe, appropriate use. “Buying Viagra without prescription” should not mean bypassing medical assessment. Instead, integrated telehealth services—such as Geisinger HealthSouth—provide a lawful, streamlined pathway in which the prescription is issued within the care process. Through a secure online intake, an Australian-registered clinician reviews your health history, medicines, and ED symptoms and, if suitable, issues an ePrescription and arranges dispensing through an Australian-registered pharmacy, consistent with Therapeutic Goods Administration (TGA) regulations.
This clinician-guided approach preserves convenience and safety: a face-to-face visit is usually unnecessary, yet you still receive professional evaluation, dosing advice, and interaction screening. Avoid websites that claim to sell “Viagra without prescription” outright, as many operate illegally and may supply counterfeit or unsafe products. Choose regulated Australian telehealth services like Geisinger HealthSouth’s program, where your assessment, prescription (including ePrescription tokens via SMS or email), and dispensing occur within one compliant system. Follow-up support is available if you experience side effects, have questions, or require dose adjustments, and your medicine is dispensed by a licensed Australian pharmacy for quality and authenticity.
