Lines appearing through text in a PDF have a few distinct causes that look similar on screen but require different fixes. The most important distinction is whether the lines are intentional formatting (strikethrough text or annotations), part of the PDF content, or a rendering artifact that doesn't actually exist in the file.
Strikethrough Formatting in the Source Document
The most common cause: the original document used strikethrough formatting, and it exported to PDF correctly. This appears in legal documents where deleted clauses are shown struck through, in track-changes edits that weren't accepted before export, or in documents where strikethrough was used stylistically.
If the strikethrough is intentional, nothing needs to be done. If it was accidental โ someone applied strikethrough formatting by mistake in the source document โ go back to the source, remove the formatting, and re-export. In Word, select the affected text and press Ctrl+D to open font formatting, then uncheck Strikethrough.
Strikethrough Annotations Added to the PDF
PDF annotation tools include a strikethrough markup tool โ it looks like a line through selected text and indicates text that should be deleted. If someone marked up the document with this annotation and you're seeing lines through text, you're looking at review annotations, not the base document content.
These annotations can be removed using a PDF Editor that supports annotation management. Open the annotations panel, select the strikethrough annotations, and delete them. Alternatively, if you need a clean version without any annotations, flatten the PDF (which makes annotations permanent parts of the page) and then remove the visual lines using a white rectangle overlay โ though this is more involved than just removing the annotations directly.
Rendering Artifact: Lines That Aren't Really There
Sometimes lines through text are a viewer rendering issue โ they appear on screen but don't actually exist in the file, and don't print. This is caused by certain PDF viewers having difficulty with specific combinations of font rendering, background colors, or transparency effects.
Test by printing the document or opening it in a different viewer. If the lines disappear in print or in another viewer, the file is fine โ it's a display artifact in your current viewer. Try Adobe Reader or Preview on Mac, which have more robust rendering than browser-based viewers for complex PDFs.
Thin Lines From the Document Layout
Some PDFs use horizontal lines as design elements โ dividers between sections, underlining for headers, or rules in table-style layouts. These are part of the document design, not text formatting. They look like lines through text when the spacing between the line element and the text above or below is tight.
If these lines are unwanted, removing them requires editing the document at the design level โ going back to the source document, removing the line elements, and re-exporting. In a finalized PDF without access to the source, covering the lines with white rectangles is the alternative, though this is imprecise and only hides rather than removes the content.
Lines Caused by Scanning Artifacts
Scanned PDFs sometimes have horizontal lines from scanner artifacts โ a speck on the scanner glass, a fold in the paper, or a calibration issue that creates consistent lines across pages. These appear as dark horizontal or vertical lines that run across the scan, sometimes through text.
For scanned documents, rescan with a clean scanner bed and proper document alignment to eliminate the source of the artifact. For existing scanned PDFs where rescanning isn't possible, image editing on individual pages can remove scan lines, though this requires extracting pages as images, editing them, and reassembling the PDF โ a significant effort for a long document.