Sildenafil

How does sildenafil work?

During sexual arousal blood flow in the penis changes. It is this change in blood flow which produces erections. Sildenafil is known medically as a PDE5 inhibitor. PDE5 inhibitors alter the levels of the natural chemical messengers involved in producing erections.

Why choose sildenafil?

Sildenafil is a tried and tested medicine. Most men find it an effective treatment and are not usually troubled by significant side effects. It usually starts to work within 30 minutes of taking a tablet, and usually remains active for about 4 hours. Erections will only occur during this time if there is stimulation. If there is no arousal, there will be no erection. After 4 hours the effects of the tablet wear off.

Alternative tablets include Cialis (tadalafil), Levitra (vardenafil), and Spedra (avanafil). They work in the same way, but for different lengths of time. See tablet differences for further details.

How to take sildenafil

The normal starting dose, in men who have not taken sildenafil before, is one 50mg tablet. Subsequent doses can be adjusted up to a maximum of 100mg as a single dose, or down to 25mg, depending on response. Most men find 50mg sufficient. Sildenafil should not be taken more than once in 24 hours.

The effects of treatment may not be exactly the same each time. It is best to take the same dose that worked previously, increasing the dose only if on several occasions treatment is not successful.

Contraindications and interactions

All men with erectile dysfunction should consult a doctor face-to-face before buying sildenafil tablets online. Sildenafil is not suitable for all men, particularly men who have severe heart disease or a history of stroke. Some prescribed medicines interact with sildenafil, most notably medicines called nitrates, used to treat angina and heart disease.

Checks on the suitability of treatment are carried out during our online consultation. Men who are not eligible to order from Dr Fox should consult with their doctors.

Men should not take sildenafil without further assessment from their GP when the following apply:

• Low or high blood pressure
• Allergies or reactions to past ED treatments
• Recent heart attack (within 6 weeks) or suffer from angina (heart pain on exertion) or any form of heart disease
• History of strokes or mini-strokes (transient ischaemic attack)
• History of vision problems caused by circulation problems
• History in the family of rare degenerative eye disease
• Serious kidney (renal) or liver disease
• Peyronie’s disease – angulation or deformity of the penis
• Leukaemia, multiple myeloma or sickle cell disease
• Bleeding disorders (such as haemophilia)
• Current active stomach ulcers (peptic ulcer or gastric ulcer)

There is a very rare theoretical risk of abnormal heart rhythm if sildenafil is taken at the same time as some other medications – please check this list.

Side effects of sildenafil

Most men find sildenafil effective and do not experience significant side effects.

The commonest side effects, affecting up to 1 in 10 men are, nausea, facial flushing, hot flush (symptoms include a sudden feeling of heat in the upper body), indigestion, colour tinge to vision, blurred vision, visual disturbance, stuffy nose and dizziness.

A complete list of side effects can be found in the manufacturer’s patient information leaflet.

Allergic type reactions, chest pains or fits, all of which are very rare, require immediate medical attention. Prolonged (2 hours or more) painful erections, a medical condition called priapism, can occur and requires immediate medical attention.

For more information see side effects of Viagra/sildenafil.

What causes erectile dysfunction (ED)?

There is no single factor which causes ED. There are many different causes. The most frequent cause is impaired circulation, which comes in part with ageing. Factors which impair circulation include smoking, lack of exercise, and obesity. Some medical conditions, most notably diabetes, are associated with ED. ED can also occur as a side effect of some prescribed medicines. Operations and trauma, which damages the nerves or blood supply to the penis, can result in ED. This is by no means a complete list.

Alternative ED treatments

Sildenafil tablets support and help natural erections. If ED is caused by severely restricted circulation or damage to the nervous system, tablets may not help.

There are alternative non-tablet treatments, including Vitaros cream, and various other locally applied treatments. Some men benefit from counselling, particularly if stress and performance anxiety are present. A GP should be able to advise.

Drug misuse

Most men take sildenafil to support their usual sexual activity, with resulting benefits to their relationships. Men often find their lives transformed.

If sildenafil is taken in combination with recreational drugs, particularly cocaine, there is an increased risk of adverse effects, particularly prolonged painful erections, which can lead to permanent damage to the penis (priapism).

Manufacturers and brands of sildenafil

Different pharmacy companies produce their own sildenafil tablets. Dr Fox supplies only UK licensed tablets supplied from UK registered pharmacies. The following pharmaceutical companies produce sildenafil: Accord, Actavis, Amarox, Bristol Labs, Crescent, Dr Reddys, Genesis, Milpharm, Mylan, Teva, RxFarma, Sandoz, Somex, Zentiva, Pfizer, and others. See manufacturers of sildenafil for more information.

Most erectile dysfunction tablets contain Lactose – Mylan sildenafil and Teva sildenafil are manufacturer brands that do not contain Lactose.

Generic medicines supplied may change from time to time as manufacturers may have stock shortages, and generic manufacturer switching is often unavoidable. Most men find no difference between generic medicines. Patients with a preference can request a specific generic manufacturer when ordering.