1. The use of a rapid-onset selective serotonin reuptake inhibitor, or a pharmaceutically acceptable salt thereof, on an as-needed basis, for the manufacture of a medicament for treatment or management of sexual dysfunction in a mammal in need of treatment wherein the medicament is adapted to administering on an as need basis. 2. The use according to claim 1, wherein said rapid-onset selective serotonin reuptake inhibitor is a short acting medicament. 3. The use according to claim 1 or 2, wherein said rapid-onset selective serotonin reuptake inhibitor is dapoxetine, or a pharmaceutically acceptable salt thereof. 4. The use according to any one of claims 1 to 3, wherein the mammal is a human male. 5. The use according to any one of claims 1 to 4, wherein the sexual dysfunction is selected from the group consisting of premature ejaculation, retarded ejaculation, low sexual desire, sexual aversion, or inhibited orgasm. 6. The use according to claim 5, wherein the sexual dysfunction is premature ejaculation. 7. The use according to any one of claims 1 to 6, wherein the medicament is administered immediately prior to, to about 12 hours prior to a sexual activity. 8. The use according to any one of claims 1 to 6, wherein the medicament is administered immediately prior to, to about 8 hours prior to a sexual activity. 9. The use according to any one of claims 1 to 6, wherein the medicament is administered immediately prior to, to about 4 hours prior to a sexual activity. 10. The use according to any one of claims 1 to 6, wherein the medicament is administered immediately prior to, to about 3 hours prior to a sexual activity. 11. The use according to any one of claims 1 to 6, wherein the medicament is administered immediately prior to a sexual activity. 12. The use according to any one of claims 1 to 11, wherein the medicament is adapted for administering from about 0.001 mg to about 350 mg of the rapid-onset selective serotonin reuptake inhibitor. 13. The use according to any one of claims 1 to 11, wherein the medicament is adapted for one dose administering from about 0.01 mg to about 200 mg of the rapid-onset selective serotonin reuptake inhibitor. 14. The use according to any one of claims 1 to 11, wherein the medicament is adapted for one dose administering from about 0.01 mg to about 120 mg of the rapid-onset selective serotonin reuptake inhibitor. 15. The use according to any one of claims 1 to 11, wherein the medicament is administered orally. 16. The use according to claim 15, wherein the medicament is administered in an oral solid dosage form. 17. The use according to claim 14, wherein the medicament is delivered in a rapid release formulation. 18. The use of dapoxetine, or a pharmaceutically acceptable salt thereof, on an as-needed basis, for the manufacture of a medicament for treatment or management of premature ejaculation in a human male which comprises administering orally to the human male about 0.01 mg to about 200 mg of dapoxetine or a pharmaceutically acceptable salt thereof immediately prior to, to about 8 hours prior to a sexual activity. 19. The use according to claim 18, wherein the medicament is adapted for administering immediately prior to, to about 4 hours prior to a sexual activity. 20. The use according to claim 18, wherein the medicament is administered immediately prior to, to about 3 hours prior to a sexual activity. 21. The use according to claim 18, wherein the medicament is administered immediately prior to a sexual activity. 22. The use according to any one of claims 1 to 21, wherein the medicament further comprising a therapeutically effective amount of an additional therapeutic agent for treating or managing a second, different sexual dysfunction. 23. An article of manufacture comprising packaging material and a pharmaceutical agent contained within said packaging material, wherein said pharmaceutical agent is effective for treating premature ejaculation in a human male, and wherein said packaging material comprises a label which indicates that said pharmaceutical agent can be used for treating premature ejaculation in a human male on an as-needed basis prior to a sexual activity, and wherein said pharmaceutical agent comprises a rapid-onset selective serotonin reuptake inhibitor or a pharmaceutically acceptable salt thereof. 24. An article of manufacture comprising packaging material and a pharmaceutical agent contained within said packaging material, wherein said pharmaceutical agent is effective for treating premature ejaculation in a human male, and wherein said packaging material comprises a label which indicates that said pharmaceutical agent can be used for treating premature ejaculation in a human male on an as-needed basis prior to a sexual activity, and wherein said pharmaceutical agent comprises dapoxetine or a pharmaceutically acceptable salt thereof. 25. An article of manufacture according to claim 24 wherein the label indicates that dapoxetine is to be administered about immediately prior to, to about 4 hours prior to a sexual activity. 26. An article of manufacture according to claim 24 wherein the label indicates that dapoxetine is to be administered immediately prior to, to about 3 hours prior to a sexual activity. 27. An article of manufacture according to claim 24 wherein the label indicates that dapoxetine is to be administered immediately prior to a sexual activity.