When missing a dose The missed dose may be recuperated as soon as you remember. But if it comes the time for the next dose, skip the dose that you have missed. Dont exceed in Singulair amount for compensation of the missed dose. When exceeding in Singulair dosage, call for emergency medical help. For Singulair overdose the symptoms have not been studied. Side effects As any drug, order Singulair may provoke some side effects like nausea, stomach pain, headache, weakness. But if these get more serious and dont pass during some days consult your doctor immediately. The manifestation of side effects depends on your health estate and on other circumstances. Sometimes these side effects dont stop because of pour health, extenuation or in combination with other substances. That is why some people may be directed different individually determined doses.