This is false. Poison ivy (and other poison plant rashes) cannot be spread from person-to-person after the rash develops. Only contact with the oil urushiol, from the plant’s sap, can cause the poison ivy rash. In addition, if you have poison ivy, the fluid that leaks from your blisters cannot cause a rash because it does not contain urushiol. (However, it is possible to pick up the rash from clothing, pets, garden tools, and other items that have come in contact with urushiol.) Keep in mind that the blisters and redness from poison ivy can develop at different times in different parts of the body, which can make it seem like the rash is spreading.
Unfortunately, the spreading of poison ivy usually happens before you realize you have it on your skin. That’s why it’s very important to wash your hands after gardening or being out in the woods (do this before you use the bathroom). Also, be sure to wipe down any tools or equipment that you think may have contacted poison ivy. It’s a good idea to see your primary care provider if you have more than a mild case of poison ivy.