Hi.. Welcome to HEALTHCARE MAGIC.. I have gone through your query and can understand your health concerns.. As per your complain white coating on the tongue can be caused by Omeprazole which is a Proton Pump Inhibitor and it is used to treat acidic conditions of stomach like high acidity and acid reflux.. Proton pump inhibitors like Omeprazole causes decreased saliva production causing Dry Mouth and it can lead to fungal infection known as THRUSH which causes cheesy white coating on tongue.. Also there is increased pH of saliva by taking Omeprazole due to reduced stomach acid there is a better environment for the growth of the fungus as well as alteration in the microbial flora of the mouth which helps in preventing infections leading to progression of infection.. I would suggest you to consult an Oral pathologist and get evaluated and in case of thrush: -You will be given a reduced dose of the medicine or medicine will be changed if possible.. -The doctor will give you a course of oral antifungal medicines like Fluconazole or Itraconazole for a period of 14 days.. -Nystatin mouthwashes can help.. -Antifungal lozenges can help.. -Take more of probiotics like Yoghurt and garlic in diet.. -Avoid antibiotic containing mouth rinses.. -If you experience dry mouth Saliva substitutes like Methyl cellulose can be instilled in mouth.. -Saliva stimulants like lemon drops and sour candies can stimulate saliva flow.. Hope this information helps and thanks for writing to Healthcare Magic.. If you find the answer the please give a Five Star Review and click on found the answer helpful as a token of appreciation.. Thanks and regards. Dr.Honey Nandwani Arora..