Sildenafil citrate 150 mg is used to help treat erectile dysfunction (ED) in men by improving blood flow to the penile tissues. It works by inhibiting the phosphodiesterase-5 (PDE-5) enzyme, which relaxes blood vessels and allows increased blood circulation during sexual stimulation, helping achieve and maintain a firm erection. The 150 mg strength is considered a higher-than-standard dose and may be used when lower strengths are not effective, but it should only be taken under strict medical supervision. It is typically taken about 30–60 minutes before sexual activity and should not be used more than once in 24 hours. Possible side effects include headache, flushing, dizziness, nasal congestion, blurred vision, and indigestion.