We normally advise you to avoid eating a substantial meal 2-3 hours before the treatment and to use the toilet before to your appointment. The faster and more efficiently the nitrous oxide gas acts, the less you talk or breathe through your mouth. This is important as any food or liquid in your mouth will slow down how quickly the gas works. However, if you are feeling very nervous or anxious about your treatment we would recommend that you eat something before you go into the therapy room. This will help fill your stomach and take some of the pressure off your lungs. Once you have been treated with nitrous oxide you should be able to eat whatever you like without affecting the effectiveness of your therapy. However, it is recommended that you don't eat anything fatty or heavy just before you go into treatment. If you suffer from asthma or another respiratory condition we recommend that you speak to your doctor first before eating anything close to your treatment. Some people with respiratory problems may be advised not to eat certain foods during an attack. Your therapist will tell you what to expect during your treatment and how much time you should allow for it. They will also let you know if there are any particular foods that might affect the speed at which nitrous oxide works in your body.