Hello and Welcome to ‘Ask A Doctor’ service. I have reviewed your query and here is my advice. The active ingredient of ZzzQuil is diphenhydramine which is very similar to claritin (loratadine). Diphenhydramine is a first generation antihistamine and loratadine a second generation one. The main difference is on their prominent effects. Diphenhydramine (and many other drugs from the first generation category) cause sleepiness so frequently that they re commonly used against insomnia. Loratadine does not usually cause sleepiness (less than 10% of patients may experience it). Taking two drugs of the same drug class is a little risky since they usually share the same side effects and effectively doubling the dosage (taking two drugs) increases the risk for experiencing them. Since loratadine is usually not sedative, I doubt that you re going to have problems with it but nobody can say for sure until you try. Your other disorders (asthma, fatty liver) won t be affected by concurrent use. Hope I have answered your query. Let me know if I can assist you further.