diff --git a/base/essentials.jl b/base/essentials.jl
index dd410b06cc8d9..d57ef023e6283 100644
--- a/base/essentials.jl
+++ b/base/essentials.jl
@@ -775,6 +775,13 @@ inferencebarrier(@nospecialize(x)) = Ref{Any}(x)[]
 
 Determine whether a collection is empty (has no elements).
 
+!!! warning
+
+    `isempty(itr)` may consume the next element of a stateful iterator `itr`
+    unless an appropriate `Base.isdone(itr)` or `isempty` method is defined.
+    Use of `isempty` should therefore be avoided when writing generic
+    code which should support any iterator type.
+
 # Examples
 ```jldoctest
 julia> isempty([])