Fildena CT 100 (sildenafil 100 mg) can seem to lose effectiveness, but that doesn't necessarily mean your body has become tolerant to it. Common reasons include: Timing: taking it too close to sex or not allowing enough time to work. Food: a heavy/high-fat meal can delay sildenafil's effect. Alcohol: especially larger amounts, can reduce erection quality. Insufficient sexual stimulation or anxiety/stress. Changes in health: diabetes, high blood pressure, obesity, hormonal issues, or cardiovascular problems can affect erections. Fildena CT 100  interactions can also reduce its effectiveness. Counterfeit or poorly stored medication is another possibility with products obtained from unreliable sources. Sildenafil doesn't usually develop significant tolerance in the way some medicines do. Don't increase beyond 100 mg or take another dose the same day if it doesn't work. If it used to work reliably and has stopped working, it's worth discussing with a doctor rather than simply increasing the dose. If you tell me how long you've been using Fildena CT 100 and how/when you take it, I can help identify the most likely reason.