Is it safe to take the anti depressant celexa (30mg) with a vitamin b1?

Yes, generally. Vitamin b1 is thiamine. Like other b complex vitamins, thiamine is sometimes called an "anti-stress" vitamin because it may strengthen the immune system and improve the body's ability to withstand stressful conditions. It is named b1 because it was the first b vitamin discovered. A dose of 50-100mg/day is often used as a supplement -- but it can appear in a good basicl multivitamin too.