For all its promise, nuclear radiation is a relatively new and dangerous tool; and nuclear radiation exposure can cause radiation sickness from an acute exposure. Symptoms of radiation poisoning include nausea, hair loss, and vomiting. In the long run, radiation side effects can include the above but also various cancers.
If you are concerned that you have suffered or will suffer a radiation exposure, there are precautions you can take. Potassium iodide or KI pills (in a 130 mg dose) are the typical prophylactic treatment for radiation poisoning, if you know you are about to suffer a radiation exposure. You may more easily find or have heard of SSKI (a saturated solution of potassium iodide), two drops of which represent an effective treatment for adults (adolescents 3-18 years of age should receive a half-dose of any iodine treatment). If you live in the vicinity of a nuclear power plant, you can very likely get free KI pills to keep as First Aid for your family in the event of a radiation release.
KI only protects against a specific type of exposure, but it is proven very effective in preventing thyroid cancer. The iodine in the pill or solution prevents the body from taking up the radioactive iodine released in a nuclear accident. This threat is the most critical in a nuclear emergency, and so KI or SSKI treatment is highly recommended before and during exposure. The idea is that the KI fulfills the body’s/thyroid’s daily requirement for iodine, so that there is no space left to take up the poisonous radioiodine. This means you should take the recommended KI or SSKI dosage at least several hours before the predicted arrival of any radiation release and continue taking maintenance doses until the danger has passed.