Cenforce 100 can be very effective in treating ED, but it's not right for everybody. That's because Cenforce 100 mg was the first oral pill to treat ED. It was approved by the U.S. 

Cenforce side effects are temporary or say minor. 12. Stanopoulos I, Hatzichristou D, Tryfon S, Tzortzis V, Apostolidis A, Argyropoulou P "Effects of sildenafil on cardiopulmonary responses during stress." J Urol 169 (2003): 1417-21. 34. PadmaNathan H, Steers WD, Wicker PA "Efficacy and safety of oral sildenafil in the treatment of erectile dysfunction: A double-blind, placebo-controlled study of 329 patients." Int J Clin Pract 52 (1998): 375-9. It is possible that some side effects of sildenafil may not have been reported.
It is a confusing area, but essentially, if men stick to buying their erectile dysfunction treatments from UK regulated websites, they can be confident that whether they buy Cenforce or sildenafil, they will get medically identical UK licensed medicine. Other side-effects are listed in the table at the bottom of the page and are repeated in the ‘patient information leaflets' supplied with the medication - see link below. As Cenforce and sildenafil are medically the same, they have the same side-effects and interact with other medicines in the same way.

More detailed information taken from ‘Summary of Product Characteristics' of Cenforce (the drug license document, data provided by manufacturers for product licensing) is copied below under the following headings (correct as of October 2016): Prior to prescribing sildenafil, physicians should carefully consider whether their patients with certain underlying conditions could be adversely affected by such vasodilatory effects, especially in combination with sexual activity. Interactions with other treatments for erectile dysfunction.
In order to minimise the potential for developing postural hypotension, patients should be hemodynamically stable on alpha-blocker therapy prior to initiating sildenafil treatment. Although no increased incidence of adverse events was observed in these patients, when sildenafil is administered concomitantly with CYP3A4 inhibitors, a starting dose of 25mg should be considered. Co-administration of the HIV protease inhibitor saquinavir, a CYP3A4 inhibitor, at steady state (1200mg three times a day) with sildenafil (100mg single dose) resulted in a 140% increase in sildenafil Cmax and a 210% increase in sildenafil AUC.
When a single 100mg dose of sildenafil was administered with erythromycin, a moderate CYP3A4 inhibitor, at steady state (500mg twice daily for 5 days), there was a 182% increase in sildenafil systemic exposure (AUC). Although specific interaction studies were not conducted for all medicinal products, population pharmacokinetic analysis showed no effect of concomitant treatment on sildenafil pharmacokinetics when grouped as CYP2C9 inhibitors (such as tolbutamide, warfarin, phenytoin), CYP2D6 inhibitors (such as selective serotonin reuptake inhibitors, tricyclic antidepressants), thiazide and related diuretics, loop and potassium sparing diuretics, angiotensin converting enzyme inhibitors, calcium channel blockers, beta-adrenoreceptor antagonists or inducers of CYP450 metabolism (such as rifampicin, barbiturates). Concomitant administration of sildenafil to patients taking alpha-blocker therapy may lead to symptomatic hypotension in a few susceptible individuals.
When sildenafil and doxazosin were administered simultaneously to patients stabilized on doxazosin therapy, there were infrequent reports of patients who experienced symptomatic postural hypotension. Pooling of the following classes of antihypertensive medication; diuretics, beta-blockers, ACE inhibitors, angiotensin II antagonists, antihypertensive medicinal products (vasodilator and centrally-acting), adrenergic neurone blockers, calcium channel blockers and alpha-adrenoceptor blockers, showed no difference in the side effect profile in patients taking sildenafil compared to placebo treatment.
More info about Cenforce 100 mg internet page: read this.