Viagra (sildenafil) Tablets

Viagra is a prescription medicine for erectile dysfunction (ED), which is difficulty getting or keeping an erection firm enough for sex, and it works by improving blood flow in penile tissue when sexual stimulation is present. This page explains how sildenafil citrate functions, what directions on a prescription label commonly cover, and the safety topics clinicians usually review; it also outlines access steps with US shipping from Canada and a cash-pay option that may help people without insurance. The details below are general, so the dispensing label and prescriber instructions remain the main reference, especially when there is heart disease, low blood pressure, liver or kidney problems, or medicines that affect circulation.

What Viagra Is and How It Works

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This medicine contains sildenafil citrate, a phosphodiesterase type 5 (PDE5) inhibitor (a medicine that helps blood vessels relax). In ED, the goal is to support normal erectile response by increasing cyclic GMP (cGMP), which helps smooth muscle in the penis relax and allows more blood to enter during arousal. The treatment does not create sexual desire, and it typically requires sexual stimulation to work.

ED can be related to blood vessel disease, diabetes, nerve injury, hormonal issues, stress, depression, smoking, or medication effects. Because ED may be an early sign of cardiovascular disease, a clinician may ask about exercise tolerance, chest pain, and stroke risk factors before prescribing. A medication review is also important, since some drug combinations can cause unsafe drops in blood pressure.

Who It’s For

Viagra is indicated for adult men with erectile dysfunction when a prescriber determines it is appropriate. It is not approved for children, and it is not the same as products sometimes marketed as “female viagra,” which generally refer to different conditions and different drugs. People with ED may also benefit from evaluation for contributing conditions such as diabetes, sleep apnea, depression, or low testosterone, since treating the underlying cause can improve outcomes over time.

Key situations where this therapy may be unsafe include use of nitrate medicines (often used for chest pain), because the combination can lead to severe hypotension (dangerously low blood pressure). Many patients are also advised to use extra caution if they have significant heart disease, recent heart attack or stroke, uncontrolled high blood pressure, certain eye conditions, or anatomical penile conditions that increase priapism risk. For broader navigation, browse condition and specialty hubs like Erectile Dysfunction, Mens Health, and Urology, and see related context on Diabetes And Erectile Dysfunction.

Dosage and Usage

Most labeling for sildenafil in ED describes “as needed” use rather than a scheduled daily dose. Prescribers commonly instruct patients to take a single tablet before anticipated sexual activity, and not to take more than one dose in a 24-hour period. Dose selection can depend on response, tolerability, age, and other health conditions, and the prescriber may adjust the strength over time based on safety and effect.

When required, the prescription is confirmed with the prescriber.

Timing and food considerations

For Viagra, directions often specify taking it about 30 minutes to 4 hours before sexual activity, with many people using a window of roughly 1 hour. It can be taken with or without food, but a high-fat meal may delay the onset. Because sildenafil can lower blood pressure, dizziness is possible, especially when standing up quickly or when combined with alcohol. If a dose is missed in an “as needed” plan, it is typically not “made up” later; the label and prescriber directions guide what to do.

Why it matters: Meal timing and interacting medicines can change both effect and side effects.

Strengths and Forms

This product is supplied as an oral tablet. Common strengths used for ED include 25 mg, 50 mg, and 100 mg, and the prescribed strength should match the directions on the dispensing label. Availability can vary by pharmacy and jurisdiction, so the exact presentation dispensed may differ even when the active ingredient is the same.

Some patients also see sildenafil in other strengths for different indications, such as 20 mg tablets that are typically associated with pulmonary arterial hypertension regimens; those directions and dosing schedules are not interchangeable with ED instructions. If a prescriber changes a strength or switches between brand and generic sildenafil, the safest approach is to compare the new label directions with the prior ones and clarify any differences before use.

Storage and Travel Basics

Tablets are generally stored at controlled room temperature in a dry place, protected from excess heat and moisture. Keep the medicine in its original packaging until use to help protect it from humidity. Bathrooms and cars can expose medicines to temperature swings, so they are usually not ideal storage locations.

For travel, keeping tablets in a carry-on bag helps prevent loss and reduces exposure to extreme temperatures in checked luggage. If traveling across time zones, the key reference is still the “once per 24 hours” limit found in many ED directions. Carrying a current medication list can also help if urgent care is needed while away from home.

Quick tip: Keep tablets with the pharmacy label for easier identification during travel.

Side Effects and Safety

Common side effects with Viagra may include headache, flushing, nasal congestion, indigestion, nausea, dizziness, and visual color changes or blurred vision. These effects are often dose-related and may be more noticeable when alcohol is used or when a person is dehydrated. If side effects are persistent, a prescriber may reassess the dose, timing, or whether another ED approach is safer.

Approved orders are filled by licensed Canadian pharmacies.

Serious reactions require urgent medical attention. Seek emergency care for chest pain, fainting, severe shortness of breath, an erection lasting more than 4 hours (priapism), or sudden vision or hearing loss. Rare but important risks also include severe allergic reaction (hives, swelling, trouble breathing) and significant blood pressure drops, especially when contraindicated drugs are involved. Background conditions such as diabetes and vascular disease can affect both ED and overall risk; related reading includes Type 2 Diabetes Overview and Intimacy And Diabetes.

Drug Interactions and Cautions

Viagra must not be taken with nitrates (including nitroglycerin products) due to the risk of profound hypotension. Another major contraindication is use with riociguat, a guanylate cyclase stimulator, because it can further amplify blood-pressure lowering. Clinicians also review alpha-blockers used for urinary symptoms (for example, tamsulosin) and some blood pressure medicines, since combined effects can increase dizziness or fainting risk.

Medicines and substances that often need review

Many interactions relate to metabolism through CYP3A4 (a liver enzyme that processes many drugs). Strong CYP3A4 inhibitors (such as some antifungals, certain antibiotics, and some HIV medicines) can raise sildenafil exposure, which may increase side effects. Grapefruit products may also affect metabolism in some people. Using more than one PDE5 inhibitor at the same time (for example, tadalafil plus sildenafil) is generally avoided unless a prescriber provides specific instructions. Alcohol can add to lightheadedness, so intake is commonly discussed as part of counseling.

Because ED can overlap with prostate and urinary symptoms, a medication review may cover both areas. Background reading on related issues is available in Urology Articles.

Compare With Alternatives

Compared with Viagra, other PDE5 inhibitors may differ mainly in timing and duration, not in the overall goal of improving erectile response. A common alternative is tadalafil, which is longer-acting for many patients; see Cialis for the product listing. Other prescription options in this class include vardenafil and avanafil, which have their own labeling and interaction profiles.

Non-oral approaches may be considered when tablets are not effective or are not safe, including vacuum erection devices, penile injections, urethral suppositories, or addressing contributing conditions such as sleep problems and depression. ED is distinct from fertility, although they can co-exist; for related context, see Diabetes And Male Fertility. A clinician can help decide which approach aligns with cardiovascular risk, other medicines, and treatment preferences.

Pricing and Access

Access to prescription ED therapy typically requires a valid prescription and a clinical review of contraindications and interactions. CanadianInsulin coordinates the documentation needed for dispensing through partner pharmacies, which can be useful for people seeking cash-pay access outside insurance coverage. Educational hubs such as Mens Health Articles can support informed discussions about sexual health and chronic disease.

Cash-pay access is available, including for people without insurance.

When budgeting, it may help to consider the prescribed strength, how frequently it is used, and whether a prescriber is considering a different PDE5 inhibitor. Any site-wide programs are listed on Promotions. For deeper background on metabolic health and sexual function, see Link Between Diabetes And Erectile Dysfunction and Diabetes Signs In Men.

Authoritative Sources

For the most reliable details on contraindications, warnings, and studied dosing, consult official labeling and reputable public-health references. These sources are especially helpful when reviewing nitrate use, cardiovascular precautions, or serious adverse events such as priapism and sudden vision changes.

Bring questions from these references to a prescriber or pharmacist, and compare them with the dispensing label directions. If there is uncertainty about interaction risk, a pharmacist can usually clarify whether another medicine in the regimen raises sildenafil exposure.

• For U.S. prescribing information and approval details, see FDA Application Overview.
• For patient-friendly medication guidance, review MedlinePlus Sildenafil Information.

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This content is for informational purposes only and is not a substitute for professional medical advice.