Sildenafil Tablets

Sildenafil is a popular medication used to treat men with erectile dysfunction (ED), which is the inability or difficulty in achieving or maintaining an erection. Sildenafil is the generic version, and the active ingredient of Viagra and works to improve the blood flow to the penis. It is available in different strengths to provide the correct dose to help you manage your condition easily.

Sildenafil is commonly prescribed to treat erectile dysfunction but it may be prescribed by specialists for other conditions such as pulmonary hypertension.

Sildenafil belongs to a family of medications called phosphodiesterase-5 (PDE-5) inhibitors. In short, it helps relax the blood vessels to improve blood flow and therefore assists in achieving and maintaining an erection following sexual arousal.

Sildenafil blocks the breakdown of cGMP by an enzyme called phosphodiesterase-5 (PDE-5). Nitric Oxide, a vasodilator can then bind to the receptors in the penis resulting in increased levels of cGMP and causing muscle relaxation and higher blood flow into the penis. By stopping the PDE-5 from blocking this process, sildenafil helps with achieving an erection.

It’s important to note that sildenafil does not resolve the underlying cause of ED and does not cause an erection on its own. You will need to be sexually stimulated for the medication to work.

Studies have found that sildenafil is a highly effective treatment for erectile dysfunction. 62% of men on 25mg dose, 74% of men on 50mg and 82% of men on the 100mg dose reported improved erections.

Sildenafil will work for most men, depending on their dose and personal factors such as age and weight. Remember that you need to be sexually aroused for it to work. If you don’t notice the effects initially, we recommend trying the medication on 8 separate occasions before considering a higher dose or a different ED treatment.  

For the best results and effect of sildenafil, it is recommended to take it on an empty stomach. This is so that sildenafil can be fully absorbed into the bloodstream as some foods, particularly fatty foods, can make it harder to enter the system and work quickly.

Although sildenafil takes around 30 minutes to start taking effect, it peaks approximately 60 minutes after taking it.

Depending on several factors, sildenafil’s effects can last up to 4 hours.

Some factors that affect how long sildenafil lasts include the dosage you have taken, your weight and age, your mindset at the time, and whether you have taken it on an empty stomach. You can read more about this here.

Sildenafil can remain in your bloodstream for up to 12 hours. However, patients will experience the main effects of sildenafil within 4 hours of taking the tablet. This is because the peak concentration in the blood is usually achieved within 1 hour of taking the tablet. After 4 hours, the concentrations are not high enough to provide you with any benefit.

Food can dampen the effects of sildenafil. This is backed by a study highlighting this impact. As you can see below, sildenafil concentrations peak much higher when taken on an empty stomach than in patients who have eaten. Food slowed the rate but minimally affected the extent of drug absorption.

Figure 1: Mean plasma concentration profiles of sildenafil following oral (○) and intravenous (•) administration of 50-mg sildenafil.

Most men over the age of 18 can take sildenafil if they are experiencing signs of erectile dysfunction.

When completing a consultation, it’s important to let us know about your full medical history so that we can ensure this is the safest treatment for you.

The recommended dose is 50 mg taken approximately one hour before sexual activity. The dose may be increased to 100 mg or decreased to 25 mg based on effectiveness and side effects. The maximum recommended dose is 100 mg.

Only take ONE sildenafil tablet (regardless of the strength) each day. We advise taking it on an empty stomach to help avoid delays to its absorption.

Never take more than your prescribed dose within 24hours and only take a dose when you need it, as advised by your prescriber. It is unsafe to combine it with other medicines for ED.

The most common side effects of sildenafil and methods of overcoming them include:

• Headaches: Drink plenty of water and stay hydrated. Take some painkillers if your headache persists the following day. If your headache is not severe or persistent, then immediately consult The Family Chemist.
• Flushing: try to cool down by drinking cold water, turning on a fan or opening a window. Avoid alcohol, as this can make flushing worse. It may also help to lie down and rest after.
• Indigestion: You can take sildenafil after food to lower the risk of indigestion. However, the effects may take slightly longer. You can consider taking antacids or alginates to lower the risk; however, if indigestion persists, try an alternative ED tablet.
• Nasal congestion: Consider adding some aromatherapy in the room to help with nasal congestion and to set the mood right.
• Dizziness: Lie down and take it easy. Avoid sudden movements or jumping up. The effects should only last for a short period of time. If they continue, stop the medication and contact your prescriber, or if possible, take your blood-pressure reading.
• Muscle pain: consider asking your partner for a massage to add to the sexual arousal and a stronger enhanced erection.

Stop taking sildenafil if:

• Experience vision changes such as blurred vision, sensitivity to light or sudden vision loss.
• Sudden decrease or loss of hearing.
• Long-lasting and painful erections which can cause permanent damage to the penis.
• Low blood pressure.

Please visit the patient information leaflet for Sildenafil for a full list of side effects.

People who have experienced a stroke or severe heart disease should not take sildenafil, as this can worsen the condition. Sildenafil also interacts with many medications and may not be suitable to take.

Do not take Sildenafil:

• If you are allergic to sildenafil or any other ingredients of this medicine.
• If you are taking medicines called nitrates, the combination may lead to a dangerous fall in your blood pressure. Tell your doctor if you are taking any of these medicines often given to relieve angina pectoris (or “chest pain”). If you are not sure, ask your doctor or pharmacist.
• If you are using any of the medicines known as nitric oxide donors, such as amyl nitrite (“poppers”), the combination may also lead to a dangerous fall in your blood pressure.
• If you are taking riociguat. This drug treats pulmonary arterial hypertension (i.e., high blood pressure in the lungs) and chronic thromboembolic pulmonary hypertension (i.e. high blood pressure in the lungs secondary to blood clots). PDE5 inhibitors, such as sildenafil, have been shown to increase the hypotensive effects of this medicine. If you are taking riociguat or are unsure, inform your prescriber.
• If you have a severe heart or liver problem.
• If you have recently had a stroke or a heart attack, or if you have low blood pressure.
• If you have certain rare inherited eye diseases (such as retinitis pigmentosa).
• If you have ever had loss of vision due to non-arteritic anterior ischaemic optic neuropathy (NAION)

Talk to The Family Chemist clinician or doctor:

• If you have sickle cell anaemia (an abnormality of red blood cells), leukaemia (cancer of blood cells), multiple myeloma (cancer of bone marrow)
• If you have a deformity of your penis or Peyronie’s Disease.
• If you have problems with your heart. Your doctor should carefully check whether your heart can take the additional strain of having sex.
• If you currently have a stomach ulcer, or a bleeding problem (such as haemophilia).
• If you experience sudden decrease or loss of vision, stop taking Sildenafil
  and contact your doctor immediately.

• You should not use sildenafil with any other oral or local treatments for erectile dysfunction.
• You should not use sildenafil with treatments for pulmonary arterial hypertension (PAH) containing sildenafil or any other PDE5 inhibitors.
• You should not take sildenafil if you do not have erectile dysfunction.
• You should not take sildenafil if you are a woman.
• You should tell your doctor if you have kidney or liver problems. Your doctor may decide on a lower dose for you.

First, we recommend using sildenafil on at least eight occasions before ruling out its effectiveness. However, if you suffer from side effects, then it may be worth trying another ED tablet like Tadalafil. Tadalafil is longer-acting and can be used daily at lower doses if you have regular sex. If tadalafil doesn’t suit you, you can try Vardenafil or Avanafil. After exhausting all tablets, it may be worth revisiting the GP and considering tackling the secondary causes, for example, stress and anxiety that may be causing erectile dysfunction.

There is an alternative cream called Vitaros available from The Family Chemist, which may provide some benefit over ED tablets. Read all about it here.

50mg is the standard dose and most people will be prescribed this as long as they do not have other medical conditions.

If you experience side effects on the standard dose, or if you have certain medical conditions, we would recommend 25mg dose instead to ensure your safety.

If 50mg is not effective for you and you have not experienced side effects, we may advise an increase to 100mg dose. This is the highest possible dose.

You can take sildenafil every day, as long as you don’t exceed the maximum prescribed dose for you and you do not take more than ONE tablet in a 24hour period.

Sildenafil is safe to take with many other medicines. However, like all medicines, it can interact with a few medicines, such as nitrates for angina. The Family Chemist always recommends that you fill out the consultation accurately and provide a full list of the medicines you are taking. The Family Chemist clinician will check for interactions during the assessment phase of your online consultation.

You should never take more than ONE tablet in a 24hour period.

Sildenafil and Viagra have the same effect. Sildenafil is the active ingredient in both of them, but the benefit of Sildenafil is the cost of it as it is cheaper. The difference between them is that Sildenafil is the unbranded version of Viagra, but they both work in the same way.

No, Viagra and sildenafil are pharmacologically the same. Viagra is the brand name of Sildenafil. The pharmacokinetic data and pharmacological response are the same; therefore, the cautions, contraindications and adverse reactions are the same. Viagra is the same effectiveness as sildenafil.

We would recommend avoiding alcohol while on sildenafil, or drinking in moderation. Excess drinking of alcohol can contribute to Erectile Dysfunction. Alcohol interferes with the blood flow and can affect getting an erection. According to a study consuming alcohol dampens your central nervous system and slows down the communication between the brain and the penis. Alcohol is a diuretic, increasing urination and making you feel dehydrated. Dehydration leads to a release of the hormone angiotensin, which narrows blood vessels and can limit blood flow to the penis.

Another study found that alcohol can lead to a drop in circulating testosterone. Testosterone deficiency mimics nitric oxide production, the key to vasodilatation and increased blood flow to your penis.

This means that the high levels of alcohol can make the sildenafil less effective.

Sildenafil is not safe to take with recreational drugs. They have not been tested in studies and have no evidence behind their combined use. Sildenafil is particularly dangerous with:

• Poppers (amyl nitrate)
• Stimulants like MDMA (ecstasy) or cocaine
• Hallucinogens like LSD
• Legal highs or novel psychoactive substances like mephedrone.

The choice of treatment depends of the frequency of sexual intercourse and response to treatment. Sildenafil, Avanafil and Vardenafil are short acting drugs and are suitable for occasional use when required. Tadalafil is a longer acting drug which can be used when required, but can also be used as a regular lower daily dose to allow for spontaneous sexual activity or in those who have frequent sexual activity.

Sildenafil is safe to take for a long time and we recommend taking it on at least 8 different occasions to see if it agrees with you. There do not seem to be any lasting harmful effects from taking sildenafil for many months and years. The effects of sildenafil can vary from time to time as achieving an erection depends on many factors, including food, alcohol, arousal, weight, and comorbidities such as high blood pressure or diabetes. You should consult your doctor if there has been a change to your medical history or if the usual dose of sildenafil repeatedly fails to help you maintain an erection.

No, ED treatments taken together can significantly increase the risk of dangerous and toxic side effects. They can increase the risk of falls, fainting, cardiac arrests, tachycardia and prolonged, painful erections, causing permanent damage to the penis.

The safe method would be to try an ED treatment at a middle dose, and if it’s ineffective, work your way up to the maximum tolerated dose and try the dose at least eight times with at least 24 hours between each dose. Try another ED medicine if you find the ED treatment intolerable or ineffective. Leave at least 24 hours between doses and sometimes more if taking tadalafil.

Sildenafil is the generic version of Viagra. Branded products tend to be more expensive, especially during their patent.

We recommend avoiding grapefruit or grapefruit juice as it can interfere with sildenafil’s absorption in your body and can increase the risk of side effects.

You can get Viagra Connect from most pharmacies, you would need to do a short consultation with a pharmacist but may be able to have it without a prescription.

All other versions of sildenafil will require a prescription from a qualified prescriber.

Yes. We recommend checking the provider’s website carefully to ensure they are registered and reliable. The Family Chemist is a GPhC-registered pharmacy providing MHRA-approved medications so you can trust our products and get advice from qualified clinicians.

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Medicines and Healthcare products Regulatory Agency (MHRA). Sildenafil SmPC. [accessed 25th March 26]

European Medicines Agency (EMA). Sildenafil assessment report. [accessed 25th March 26]

NHS. Erectile dysfunction (impotence). [accessed 25th March 26]

NICE Clinical Knowledge Summaries. Erectile dysfunction. [accessed 25th March 26]

NHS. Sildenafil: side effects and advice. [accessed 25th March 26]

Sildenafil Patient Information Leaflet, emc [accessed 25th March 26]

A Meta-Analysis of Erectile Dysfunction and Alcohol Consumption, National Library of Medicine. [accessed 25^th March 26]