Erectile dysfunction or impotence is a condition that affects many men during their lives. Usually, this issue is associated with aging and is more common in older men. It can also be a symptom of underlying conditions like diabetes, depression, or heart disease. More information

A doctor will review your order and write you a prescription, if appropriate. This prescription is then forwarded to a pharmacy. The pharmacy will have your medicine delivered to you within one to three working days. Read more about this process here.

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Sildenafil is a medication used to treat male sexual function issues such as impotence or erectile dysfunction. When combined with stimulation, the Sildenafil drug will help to improve the blood flow to the penis to help men maintain an erection.  This drug will not protect against sexually transmitted diseases. Make sure that you speak to your doctor about practicing safe sex with Sildenafil.

What is Sildenafil? 

Erectile dysfunction or impotence is a condition that affects many men during their lives. Usually, this issue is associated with aging and is more common in older men. It can also be a symptom of underlying conditions like diabetes, depression, or heart disease. If you struggle to get and maintain an erection, it's crucial to speak to a doctor before seeking treatment. The problem could be a sign of a severe health issue. If your doctor feels that it is appropriate, they can prescribe Sildenafil. Sildenafil is a drug commonly used for erectile dysfunction. It is the generic form of a well-known drug named Viagra. The patent for Viagra expired during 2013, which means that many other manufacturers can now make the medication using the active ingredient of Sildenafil.

When is Sildenafil used? 

Sildenafil is the medication most commonly used to treat the condition of erectile dysfunction. The substance works by relaxing the blood vessels in the penis and increasing blood flow to your groin region. Sildenafil helps men to both get and maintain an erection when combined with sexual stimulation. Sildenafil is sometimes used to treat a condition known as pulmonary hypertension. This is a condition that is caused by high blood pressure in the vessels supplying blood to the lungs. The medication is only available on prescription and comes in the form of tablets, liquids, and chewable pills. It usually takes between 30 and 60 minutes for Sildenafil to work for people with erectile dysfunction. Users can take the medication up to four hours before they want to have sex. Importantly, this medication will not work alone; sexual stimulation is also necessary.  

How do you use Sildenafil? 

As with any medication, it is important to read the information leaflet given by your pharmacist before you take Sildenafil. If you have any concerns or questions, speak to your pharmacist or doctor. When treating erecctile dysfunction, take this drug by mouth as directed by your doctor, and as needed. You will need to take Sildenafil at least thirty minutes, but no longer than four hours before sexual activity. Do not take more than one dose of Sildenafil per day. A high-fat meal can cause Sildenafil to take longer to work than it usually would. You should only take one tablet at a time. Do not drink more than two units of alcohol with Sildenafil. Remember that Sildenafil will only work if you also become sexually aroused. When successful, the effects of Sildenafil can last for up to four to 6 hours.Speak to your doctor if your condition doesn't improve.  

What dosages are available? 

The dosage of Sildenafil that your doctor gives you will depend on several things, including prior health conditions that might be aggravated by this medication. Usually, the most common dose is a 50mg tablet taken once on the day you intend to be sexually active. In rare circumstances, a doctor may prescribe up to 100mg of Sildenafil. However, they will usually give you the 50mg pill, to begin with and work up to a greater dose if you have no success. Remember to take your dose of Sildenafil at least thirty minutes before sex. It's also important to keep in mind that the effects of Sildenafil can be stronger when you are taking the 100mg. Side effects with a larger dose may also be more pronounced.   

What are the side effects of Sildenafil? 

More most people, Sildenafil is a useful treatment for erectile dysfunction. However, like any medication, there is a possibility that you will experience side effects when taking this drug. Most of the side effects will be mild and pass on their own. For instance, flushing, stomach upset, headaches and dizziness may occur. Some people taking Sildenafil also experience blurred vision, increased sensitivity to light, or trouble telling colors of green and blue apart. If any of these conditions occur in your case or persist, make sure that you speak to a doctor or pharmacist. Most people taking Sildenafil do not have serious side effects, but in rare cases, bad reactions may occur. If you have heart problems, remember that sexual activity can put a strain on your heart. If, when taking Sildenafil, you have sensations of dizziness, nausea, or fainting, contact a doctor and seek medical help immediately.

It is also essential to call an ambulance if you have pain in your left arm, chest or jaw. In rare cases, sudden vision problems, temporary blindness, and other vision issues can occur. If this problem happens, make sure that you stop taking Sildenafil and seek help immediately. You have a slightly higher risk of experiencing vision problems with Sildenafil if you are over the age of 50 or you smoke. Rarely, sudden decreases or loss of hearing can occur too. Make sure that you seek medical help if you experience ringing in the ears, or difficulty in hearing. When taking any erectile dysfunction medication, if you experience a prolonged or painful erection that lasts for more than 4 hours, stop taking the drug immediately. Get medical help straight away if your erection lasts for more than 4 hours. Severe allergic reactions to Sildenafil are rare. However, if you notice a rash, itching, swelling, or trouble breathing, contact a doctor immediately.  

When shouldn't you use Sildenafil? 

Sildenafil will not be the correct treatment for erectile dysfunction in all cases. Usually, this substance can be taken by men over the age of 18, and it is not intended for children or women. Do not take Sildenafil if you know that you have an allergic reaction to Viagra or any similar medications. You should also not be taking Sildenafil if you: 

  • Are taking nitrates for angina or chest pain 
  • Have recently had a heart attack or stroke 
  • Have low blood pressure issues 
  • Have a serious liver or heart condition 
  • Have a rare eye disease like retinitis pigmentosa 
  • Suffer from sickle cell anemia 
  • Have multiple myeloma 
  • Have Leukemia 
  • Have a deformity in your penis or Peyronie's disease 
  • Have a heart problem  
  • Have stomach ulcers or stomach bleeding problems 

Taking Sildenafil can make some people feel dizzy and cause vision problems. Alcohol can worsen this condition. Avoid using heavy machinery and do not drive, or do anything that requires you to be alert and have clear vision until you are sure you can do so safely. If you are concerned about any history of heart problems in your family, speak to your doctor before taking Sildenafil. Remember that most people taking this drug do not experience any negative side effects. However they will have been carefully assessed by a medical professional before beginning treatment.  

Does Sildenafil interact with any other medications? 

Before you take Sildenafil, it is essential to inform your doctor of any other medications that you are taking or have been taking in the last month. Remember that herbal medicines and drugs that are not given to you by prescription can still change the way that Sildenafil works. It is crucial to give your doctor a complete list of all the substances that you have been taking before they give you a prescription for Sildenafil.  

One drug that commonly interacts with Sildenafil is Riociguat. Sildenafil can also cause a severe drop in blood pressure when it's used alongside medications to control heart pain. Sildenafil is particularly dangerous when used with nitrates, and can lead to problems like fainting, dizziness, heart attack and strike. Do not use Sildenafil with nitrates like nitroglycerin and isosorbide. Make sure that you do not take this substance with reactional drugs that contain any nitrate substances either.  

If you are taking an alpha-blocker medication for any reason, it is critical that you let your doctor know about this before taking Sildenafil. Alpha blocker medicines like tamsulosin and doxazosin to treat high blood pressure, enlarged prostate and BPH can cause your blood pressure to become low. Sometimes, this will lead to problems like fainting and dizziness. Your doctor may decide that it still worth giving you Sildenafil as treatment, however, they may give you a lower dose to reduce your risk of side effects.  

Other medications may affect the way that Sildenafil is metabolized and removed from your body. This can also affect your reaction to this drug. Examples of drugs that might interact poorly with Sildenafil include: 

  • Macrolide antibiotics like erythromycin and clarithromycin 
  • HIV protease inhibitors like saquinavir and ritonavir 
  • Azole antifungals like ketoconazole and itraconazole 
  • Hepatis C protease inhibitors such as telaprevir and boceprevir 
  • Rifampin 
  • Mifepristone 

This is not a complete list of the drugs that may interact with Sildenafil. Make sure you speak to your doctor before taking this medicine. Do not take Sildenafil when you are taking any other similar medications to treat pulmonary hypertension or erectile dysfunction.  

Where can you buy Sildenafil? 

Sildenafil is available to buy online and offline from registered pharmacies. When purchasing a Sildenafil dose or refill from a pharmacy you may need to complete a full medical check to make sure that you are eligible for treatment. To sell this product without a prescription is against the law, so be wary of any vendors who attempt to sell the drug who have not asked for a prescription. Please note that when you're ordering Sildenafil, it may come in a package with the branded name Viagra.  

Can you get Sildenafil without a prescription?  

Sildenafil is a prescription-only medication. It is not safe to take Sildenafil without a prescription, as it can react differently in different people. To sell Sildenafil without a prescription is to act against the law. Make sure that you always buy your Sildenafil from someone who asks for or provides a complete prescription.  

Your doctor will be able to conduct a full check of your medical history before prescribing Sildenafil to make sure that it is safe for you to use.




Aurobindo Pharma, Milpharm Ltd. Accessed on 25th of April 2019, Sildenafil 100 mg film-coated tablets, retrieved from: 

NHS website, accessed on the 25th of April 2019, Sildenafil, Viagra, Retrieved from:  

NICE BNF website, accessed on 25th of April 2019, Sildenafil, Retrieved from: 

Scottish Medicines Consortium, 2011, Sildenafil Injection, Retrieved from: 

Assessed by:

Dr Wouter Mol, General practitioner
Registration number: BIG: 9057675501

Dr Wouter Mol studied medicine at the University of Groningen. From 2002 to 2003, he served as a resident in neurology, and from 2003 to 2005 he served his residency training in internal medicine and emergency medicine. Wouter Mol has been working as a GP since 2005.