Yes, a bad cold can cause bloodshot eyes. There are many causes that would lead to bloodshot eyes. One of the most common causes of bloodshot eyes is a condition known as pink eye. Pink eye is produced when the protective layer was inflamed, and this inflammation can be caused by something as simple as a cold. So, it is possible that cold cause bloodshot eyes.
You have no need to worry about it. The basically reason is the congestion of your eyes' blood circulation supplement. Then the retina in your eye ground has lack of blood circulation at a time. There have some capillaries around your eyeballs. If the hard cough shakes your head and eyeballs, these capillaries broken, your eyes appear red. When the cough is healed, the symptom will disappear. No worries! You may need some water and nutrients to supply your blood circulation, relax and have a rest, it will recovery soon. Unless the symptom will last for a long time, you have no need to worry about it.
Yes, at most occasion, having a cold will make you bloodshot in your eye, especially when you have a large amount of sleep, so at that time, pls take care of you and your eyes. Of course, when you found that your eyes are bloodshot, you cannot say it must be caused by the cold, because there are many reasons that will make your eyes bloodshot, such as the lacking of vitamins and conjunctivitis or pink eyes. By the way, when you notice your eyes are red, it should be bloodshot, and also it should not be, because when you have cold, the function of immune system will become weaker and then your eyes are easier to get infected. If so, you eyes are the same red as the bloodshot. I want to tell you that if you get cold, you should keep warm and keep on exercise in order to strengthen the immune system, which will help you to fight with the bacteria.