Hi, Thanks for posting in HCM. I understand your concern. Semen is normally whitish and little thick in consistency. Sometimes it is greyish or pale yellow in colour, which is also considered as normal. You might have noticed yellowish semen since you are taking multivitamins, which would change colour of body fluids like urine and semen. Hence, this is not abnormal. Without getting a semen analysis done, it is difficult to suggest any treatment. However, in addition, you can still take regularly medications containing L-carnitine, Alpha lipoic acid, Lecithin, Zinc, Inositol, Vitamin E and Selenium, which would provide nutrients for sperm production. Hope the information provided would be helpful. All the best.