diff --git a/packages/types/src/options.ts b/packages/types/src/options.ts
index 82123c01a380..5179c1fdb70e 100644
--- a/packages/types/src/options.ts
+++ b/packages/types/src/options.ts
@@ -286,11 +286,15 @@ export interface ClientOptions<TO extends BaseTransportOptions = BaseTransportOp
   beforeSend?: (event: ErrorEvent, hint: EventHint) => PromiseLike<ErrorEvent | null> | ErrorEvent | null;
 
   /**
-   * An event-processing callback for spans. This allows a span to be modified before it's sent.
-   *
+   * This function can be defined to modify or entirely drop a child span before it's sent.
    * Returning `null` will cause this span to be dropped.
+   *
+   * Note that this function is only called for child spans and not for the root span (formerly known as transaction).
+   * If you want to modify or drop the root span, use {@link Options.beforeSendTransaction} instead.
+   *
    * @param span The span generated by the SDK.
-   * @returns A new span that will be sent | null.
+   *
+   * @returns A new span that will be sent or null if the span should not be sent.
    */
   beforeSendSpan?: (span: SpanJSON) => SpanJSON | null;