For most people, donating blood plasma has few side effects, and whatever there may be is usually pretty mild. That being said, there are some that you should be aware of if you are considering becoming a donor.
Eat Something First!
This cannot be stressed enough. It is advised to donate blood plasma within four hours of eating a good meal. If you cannot do this for whatever reason, at least eat some snacks before you go in to donate. Otherwise you can experience such things as feeling dizzy or weak, nausea, chills and or sweating, or even fainting or "passing out". That's not to say that any of these things will definitely happen, but they certainly could.
Hold Off On The Yard Work
Additionally, doing too much physical activity or exercise right after donating can also cause many of these symptoms, especially if you are a new donor. Give your body some time to rest after donating before going for your daily jog, mowing the lawn, or going to aerobics class. Even doing too much walking around, such as going grocery shopping, can leave you feeling like your head is spinning. Literally.
Take it easy. Sit or lie down for a while if you do start feeling "off". Usually these feelings will pass after a few minutes and you can then go about your business.
Drink Plenty Of Water
You are advised to drink a lot of water the day before you donate. They will tell you that this will help your donation to go faster and easier, and they are probably right.
But there is another reason to heed this advise, not only the day before, but after the donation process is over: donating blood plasma dehydrates your body. You will probably notice that every time you donate, you feel rather thirsty. This is normal, and even to be expected. Dehydration is also a leading cause of many of the other symptoms that are associated with plasma donation, such as dizziness and weakness.
Avoid soft drinks, which actually don't help much to hydrate you. Instead, drink water, milk, or juice both the day before donating, and after you are done, especially if you do feel thirsty.
You may also notice that you feel hungry afterwards, which is another symptom you should heed. Again, don't give junk to your body; eat and drink the healthful foods it needs. You need to replenish the fluids and nutrients lost during the donation process, and sugary, fat-laden greasy junk food won't do a good job of that.
There really aren't a whole lot of worrying side effects of donating blood plasma for most people, as long as you take some careful precautiuons both before you go and after you're through.
In other words, use your brain!