It depends
The answer depends on which market the bottle came from: US Worcestershire is typically made with distilled vinegar and considered gluten-free, while UK and some European formulations use malt vinegar, which is barley.
A fermented condiment built on anchovies, tamarind, molasses, onion, garlic and vinegar, left to mature for months. The vinegar is the part that matters here, and it is the part that differs by country.
Because the same brand gives a different answer depending on which side of the Atlantic you bought it. Lea & Perrins in the United States is made with distilled white vinegar; the UK and Canadian formulations use malt vinegar, which comes from barley. Nothing on the front of the bottle tells you which one you are holding.
Read the vinegar line on the bottle in your hand. Distilled or spirit vinegar and you are fine; malt vinegar and you are not. This is the clearest case in the lexicon of why a brand name is not an answer and an ingredient list is.
Because the answer depends on the rest of the label, scanning the actual product is the only way to resolve it — CiCi checks for a gluten-free claim, the allergen statement, and which agency regulates that label, then tells you which way it lands.
Every one of these is the same ingredient. The number of names is a large part of why gluten slips past people who read every label.
Point CiCi at the barcode on the product you're holding and get this same reasoning in about two seconds, plus the carbs and the full nutrition panel. 360,000+ packaged foods are already read and waiting.
The aisle guides below cover Worcestershire sauce in context — which is usually the more useful question, because an ingredient rarely appears alone.
This answer comes from CiCi's ingredient lexicon — the same rules the scanner uses, not a separate article. Where reputable sources disagree, CiCi takes the conservative position and says so.