Whenever I'm out and there is someone near me who is sniffling, sneezing, wheezing, hacking, coughing, or just looks like death warmed over, I take a 50,000 IU as soon as I get home. I take it prophylacticly. If I feel a bit of a Sore throat, I also take one. I (and my hubby) haven't had a cold or flu in almost 4 years (since learning about Vit D3). We also take 5,000 IU daily. Although we live in Florida, we still don't get enough sunlight on our skin to make the amount of D3 we need. Taking supplemental D3 (Cholecalciferol) is not toxic like the prescription D2 is (Ergocalciferol). Be sure you get your levels checked and are not deficient. Most people are. BTW, it's best to keep your levels over 50. The levels on the blood test are to prevent disease, not optimal health. (I try to keep my levels over 80-100, but that's just me.) BTW, babies and children are being diagnosed as being abuse when in actuality they have healing rickets. Be sure you have your children's blood levels drawn and give them the appropriate supplement. Nursing mothers should consider taking a supplement to ensure adequate Vitamin D3 in their milk. Pediatricians frequently say Vit D3 is rare, then they say rickets are rare, but that's not true, especially in the northern climates. Do your research. Don't believe anything I or anyone else posts in these reviews. Most of us are not doctors, none of us know you or your situation. But the best defense is knowledge, which you get by researching things for yourself. (Antacids, like tums, will make you deficient, as well as having a high BMI, and a lot of other things. Tums are calcium carbonate and will cause rickets.)See "Dr. Mercola interviews Dr. Ayoub About Infantile Rickets" on youtube to learn more about what looks like child abuse and shaken baby syndrome, but is actually a vitamin d3 deficiency