Dexmethylphenidate, sold under the trade names Focalin among others, is a central nervous system (CNS) stimulant used in the treatment of attention deficit hyperactivity disorder (ADHD) and narcolepsy. It is in the phenethylamine and piperidine classes of medications. It is the active dextrorotatory enantiomer of methylphenidate.
1 Some allergies cause digestion problems as well. There are also times when you may feel nauseous after every meal. Nausea after meals can also be accompanied with other allergic symptoms, such as, hives or rashes.  Psychological â Sometimes, nausea after eating may also occur due to psychological factors.
People suffering from this condition are usually nauseous and experience headaches. Symptoms of fatigue, weakness, headache, and nausea are fairly common and don't necessarily have to be serious or life threatening, according to MedlinePlus. Individuals suffering from these symptoms can be in need of exercise, sleep, good nutrition and a stress-free lifestyle.