diff --git a/doc/man7/EVP_KEYEXCH-DH.pod b/doc/man7/EVP_KEYEXCH-DH.pod
index a6927afefb..04ac08bce2 100644
--- a/doc/man7/EVP_KEYEXCH-DH.pod
+++ b/doc/man7/EVP_KEYEXCH-DH.pod
@@ -7,9 +7,14 @@ EVP_KEYEXCH-DH
 
 =head1 DESCRIPTION
 
-Key exchange support for the B<DH> key type.
+Key exchange support for the B<DH> and B<DHX> key types.
 
-=head2 DH key exchange parameters
+Please note that although both key types support the same key exchange
+operations, they cannot be used together in a single key exchange. It
+is not possible to use a private key of the B<DH> type in key exchange
+with the public key of B<DHX> type and vice versa.
+
+=head2 DH and DHX key exchange parameters
 
 =over 4