We take it for granted that the food we eat is safe and free of pathogens that can cause illnesses. If it's prepared in a restaurant, we trust that proper sanitation procedures are followed by employees who aren't coming to work sick. But that's not always the case, unfortunately. Food poisoning is a common illness in the U.S., making about 1 in 6 Americans sick each year, hospitalizing about 128,000 and killing 3,000, according to the Centers for Disease Control and Prevention.

Some of these cases are due to problems at home, such as not cooking or storing food properly. But some happen as a result of contamination at growers, processing plants, distributors, or at venues such as restaurants.

You may be able to sue if you were sickened as a result of contaminated food. Take the following seven steps if you think you may have food poisoning:

1. Go to the doctor or emergency room.

Food poisoning can be serious or even deadly. A doctor can determine if you actually have food poisoning or another illness, such as a stomach virus or appendicitis. If he or she suspects food poisoning, ask for further testing to confirm the diagnosis and to try to determine if a specific pathogen caused your illness.

2. Contact your local Environmental Health agency.

This organization can help investigate the source of your claim and determine if there were other victims. If necessary, its employees can work with other agencies to recall contaminated foods.

3. Write it down.

Write down any symptoms you've had, such as vomiting, diarrhea, or abdominal pain. Also write down, while it's fresh in your mind, what you've had to eat in the past several days. You may assume that the last thing you ate made you sick, but that's not necessarily true.

4. Keep good records.

Keep any receipts you have from restaurants or grocery stores to help verify your purchases. Bank records or credit and debit card receipts can also help document your claim. Also save records of your medical expenses and any lost wages.

5. Save the food and packaging.

Save any leftovers you have if you think you got sick from a restaurant or other venue. If you suspect an item you ate at home made you sick, keep any leftover food by wrapping and freezing it. Make sure to label it properly so no one eats it by mistake. Also keep the packaging it came in. It may be possible to have these items tested to determine if they made you sick.

6. Check with others.

If you dined out with a group of other people, check to see if they, too, have gotten sick. If so, ask them to keep verification of any symptoms and medical treatment they have received.

7. Make a list of possible witnesses.

If you think you think the source of your food poisoning was a restaurant, employees may be able to serve as witnesses. Perhaps they know of unsanitary conditions or an employee who came to work sick. When a worker has hepatitis, for example, this highly contagious disease can be spread via food, water, or by the infected person to potentially thousands of diners.

If you think you may have a food poisoning claim, contact a personal injury lawyer with experience in these types of cases. He or she can advise you on the best course of action.