Men with erectile dysfunction use Kamagra 100. One of the ingredients in this medication is sildenafil, which helps men's penile tissues receive more blood flow. Take this medication half an hour prior to sexual activity so that you can enjoy quality time with your partner. This medication can be taken either before or after meals. This medication takes four to six hours to take effect. Take this medication as directed by your physician. Only men between the ages of 18 and 65 may take this medication.