VIAGRA (Sildenafil) Safety Information

Side Effects

Every medicine is associated with certain side effects, which may be mild to moderate or even severe, depending on the drug and its dosage. The adverse events that are associated with sildenafil citrate therapy are mostly mild to moderate, except some rare serious adverse events.

Some of the common adverse events of sildenafil citrate are diarrhoea, urticaria-like skin rashes, vision changes, dizziness, digestion disorders with acidic imbalance, water imbalance with edema, chills, fever, flu-like reaction with nasal congestion or discharge, sinusitis, bronchitis, allergic skin reactions, thrombosis in vasculatures, abnormal low pressure, vomiting or nausea, and behavioural problems with alterations in sleep patterns.

The adverse events may differ from one person to another. The serious adverse events that are associated with Viagra are sudden hearing or vision loss, increase in myocardial infarction risks, especially in patients with medical or familial history, increased stroke risks and aneurysm problems. These serious events are experienced by less than 10% of the persons taking sildenafil citrate. Some of the post-marketing complications are being evaluated in clinical trials by Pfizer and the results are statistically less significant.

Contraindications

Sildenafil citrate is contraindicated in patients with medical or familial history of stroke, hepatic/liver problems, drug allergy to any of the phosphodiesterase drugs (PDE5 inhibitors), abnormal low pressure, kidney damage or decreased functions, hereditary macular degenerative disorders and patients with medical advice to refrain from sexual activities due to cardiac problems.

Sildenafil is also contraindicated in patients with unexplained hearing loss or visual disturbances, pregnant women and lactating mothers. This is not a complete list of contraindications and some of the other pre-existing medical problems can also worsen upon Viagra intake. However, the patient can consult the Physician to prevent these problems. Sildenafil is also contraindicated in women and children.

Drug interactions

Some of the drugs may interact with sildenafil citrate and cause increase in its activity, or the cross-reacting medicine or a decrease in activity in either of these medicines may cause other side effects.

Some of the medicines that are known to interact with sildenafil citrate are Rifampicin, organic nitrites, mononitrates, alpha-blocker medicines, diuretics, all anti-hypertensive drugs and vasodilating medicines.

Sildenafil citrate adversely affects the absorption, distribution and elimination of many other drugs but specifically anti-hypertensive drugs.

Sildenafil citrate is metabolized by Cytochrome P-450 (CYP) system that also metabolizes many of the drugs and other xenobiotics. The drugs that are metabolized by CYP gene get reacted and may result in a drug-interaction or cross-reaction, which may lead to adverse events or accumulation of the drug in the body.

Hence, it is better to avoid taking these drugs, concomitantly.