
Viagra is available in three different dosage forms – 25, 50 or 100 milligram (mg) tablets. Although some men take one 100mg tablet an hour before sexual activity, this maximum dose should only be taken if you have no other health conditions. As a rule, GPs and other healthcare professionals will recommend a starting dose of 50mg for those taking Viagra for the first time. If this does cause any side effects, it is important to consult your GP. They may suggest lowering your dose to 25mg.
Sildenafil – the active agent in Viagra – enters your system within an hour of taking the drug. This active agent causes the walls of your blood vessels to relax, which in turn allows blood to flow more easily through them. It also temporarily stops the PDE5 enzyme – the enzyme that reduces the blood flow to the part of the penis that causes an erection – from working correctly. These two factors combine to increase the blood flow into the penis to make achieving and maintaining an erection easier.
Typically, Viagra takes between 30 and 60 minutes to start working. With this in mind, you need to take the tablet at least one hour before sexual activity. However, it’s important to note that the period of time it takes for Viagra to start working may be affected by alcohol and/or drug consumption, sexual stimulation, and the amount of food in your stomarch at the time you take Viagra.
Viagra usually works for between two and three hours before effects start to diminish. However, depending on a number of factors – including your body’s metabolism, the dosage you have taken, and other external factors – Viagra can last for as long as five hours.
Although the majority of people that take Viagra do not experience any side effects, there are a small number of potential side effects that can occur that may concern you if you have not prepared yourself. These include nausea, dizziness, skin flushes, headaches, stomach upsets, muscle aches, and a slight (but temporary) change in vision (by which you see a blue tinge).
There is also a very small chance that you could develop priapism. This is a condition where you have a painful erection that lasts for more than four hours. Usually this occurs when the Viagra you have taken reacts badly with another medication or illicit drug in your system. Although it can be embarrassing, it is important to seek medical attention if you think you are experiencing this side effect.
Following a change in the law, since 2017 men in the UK have not required a prescription to purchase Viagra and other sildenafil-based products. However, if you don’t have a prescription, most UK pharmacies require you to have a consultation with a trained pharmacist who will decide if Viagra is an appropriate treatment for you. Alternatively, if you’d rather not go to a pharmacy, you can also order ED treatments online. Once again, you don’t have to have a prescription for this. However, online pharmacies such as Access Doctor may require you to complete a short online consultation.