If you have an allergy or other condition that affects how your body handles food, it can make a simple joy like eating out more complicated, but it doesn’t make it impossible. One of the keys to eating out when you have food restrictions is communication. You need to let your server know about your allergy, whether it’s intolerance to lactose (a sugar found in dairy products), wheat, or a nut allergy.

The first thing to do is to give them an idea of the severity of your allergy, leaving little room for doubt. For example, if you have a wheat allergy, you might say: “I cannot eat anything that has wheat, rye, or barley in it, even in the smallest amounts, because I have celiac disease. It will make me sick.” Or, in the case of a nut allergy: “I cannot eat anything that has nuts in it or has even been exposed to them because I am allergic and I may have a severe, even fatal reaction.”

Then, ask them about the cuisine. Some basic questions to start with are:

  • What ingredients were used? Inquire about ingredients in the main course to those used in the sauces and garnishes.
  • What oils and sprays were used?
  • Were separate utensils, pots, and pans used to prevent cross-contamination?

Explain that cross-contamination is an issue. A tiny splatter of peanut oil or using a spoon to stir pasta then to stir your wheat-free dish can cause problems for you.

Pull the ‘Chef Card’

If you’re worried your server doesn’t understand or you want to be extra safe, ask for the manager or the chef who’s preparing the food and tell them your needs. One idea experts suggest is the “chef card.” Write down what the person preparing your food needs to know on a notecard and give it to the staff.

Anticipate the Risk

If possible, do some of the work ahead of time to help minimize risks. Contact the restaurant before you get there and talk to the staff about your issue. In the age of the Internet, many restaurants have websites where they list the foods they offer, allowing you to research your choices in advance, which can be of great help. Some websites provide models of chef cards and the Gluten Intolerance Group has a function on its website that allows you to find restaurants that know how to handle gluten sensitivities. Finally, if you get the impression that a restaurant won’t be able to or is unwilling to meet your needs, consider eating somewhere else. It’s your health, after all.

Take These Tips from an Expert

Lauren Wuscher of Philadelphia has gluten and soy sensitivities. She started a website to help people with allergies and sensitivities, not just with food, but with cosmetics, travel, and more. “A very important question to ask your server if you have a severe allergy is, ‘May I please see or speak to the chef,’” Ms. Wuscher said. “If it's a good restaurant that is concerned about your needs and keeping you safe, the chef will be able to go over the menu with you and help you decide what options are best for you to choose.

“If the restaurant refuses, it's definitely somewhere you won't want to dine,” she continued. “The chef will know if he or she is able to make your food without any risk of cross-contamination and will hopefully make your meal himself to be safe.

“Another question to ask—and you can ask all of these questions even before you sit down by calling or doing a little research—is if they have ever dealt with food allergies or sensitivities before and if they have the capabilities to make you meals,” Ms. Wuscher said. “Some kitchens just don't have a separate area where they can prepare food and a lot of them fry foods in soybean oil or use a spray nonstick that could potentially have soy or wheat in it. Asking about these items in advance can really help.”