Moldy tomato sauce is dangerous. While some molds are harmless, others produce toxins (mycotoxins) that can cause illness, from digestive upset to more severe health issues. Even if you scrape off the visible mold, its roots and toxins can penetrate deeply into the sauce, making it unsafe to consume.
Once opened, tomato sauce typically lasts about 5 to 7 days in the refrigerator. This timeframe applies to both jarred and canned sauces. Beyond this period, the risk of bacterial growth and spoilage increases significantly. Always store opened sauce in an airtight container to maintain freshness and prevent contamination. If you're unsure, it's always safer to discard it.