diff --git a/DESCRIPTION b/DESCRIPTION
index 01569208a..e840243f4 100644
--- a/DESCRIPTION
+++ b/DESCRIPTION
@@ -30,7 +30,7 @@ Suggests:
     broom.helpers (>= 1.15.0),
     broom.mixed (>= 0.2.9),
     car (>= 3.0-11),
-    effectsize (>= 0.6.0),
+    effectsize (>= 0.8.8),
     emmeans (>= 1.7.3),
     geepack (>= 1.3.2),
     ggsurvfit (>= 1.1.0),
diff --git a/R/ard_effectsize_hedges_g.R b/R/ard_effectsize_hedges_g.R
index 7cd99263d..2d1a68224 100644
--- a/R/ard_effectsize_hedges_g.R
+++ b/R/ard_effectsize_hedges_g.R
@@ -30,7 +30,7 @@
 #' The data are then passed as
 #' `effectsize::hedges_g(x = data_wide[[<by level 1>]], y = data_wide[[<by level 2>]], paired = TRUE, ...)`.
 #'
-#' @examplesIf do.call(asNamespace("cardx")$is_pkg_installed, list(pkg = c("effectsize", "parameters", "withr"), reference_pkg = "cardx"))
+#' @examplesIf do.call(asNamespace("cardx")$is_pkg_installed, list(pkg = c("effectsize", "parameters"), reference_pkg = "cardx"))
 #' cards::ADSL |>
 #'   dplyr::filter(ARM %in% c("Placebo", "Xanomeline High Dose")) |>
 #'   ard_effectsize_hedges_g(by = ARM, variables = AGE)
@@ -52,7 +52,7 @@ ard_effectsize_hedges_g <- function(data, by, variables, conf.level = 0.95, ...)
   set_cli_abort_call()
 
   # check installed packages ---------------------------------------------------
-  check_pkg_installed(c("effectsize", "parameters", "withr"), reference_pkg = "cardx")
+  check_pkg_installed(c("effectsize", "parameters"), reference_pkg = "cardx")
 
   # check/process inputs -------------------------------------------------------
   check_not_missing(data)
@@ -77,19 +77,12 @@ ard_effectsize_hedges_g <- function(data, by, variables, conf.level = 0.95, ...)
         variable = variable,
         lst_tidy =
           cards::eval_capture_conditions(
-            # Need to eval in NAMESAPCE DUE TO BUG IN effectsize v0.8.7.
-            # Can remove this later along with requirements for withr to be installed.
-            # Will also need to remove `hedges_g` from globalVariables()
-            withr::with_namespace(
-              package = "effectsize",
-              code =
-                hedges_g(
-                  reformulate2(by, response = variable),
-                  data = data |> tidyr::drop_na(all_of(c(by, variable))),
-                  paired = FALSE,
-                  ci = conf.level,
-                  ...
-                )
+            effectsize::hedges_g(
+              reformulate2(by, response = variable),
+              data = data |> tidyr::drop_na(all_of(c(by, variable))),
+              paired = FALSE,
+              ci = conf.level,
+              ...
             ) |>
               parameters::standardize_names(style = "broom") |>
               dplyr::mutate(method = "Hedge's G")
@@ -143,10 +136,7 @@ ard_effectsize_paired_hedges_g <- function(data, by, variables, id, conf.level =
               .paired_data_pivot_wider(by = by, variable = variable, id = id) |>
               tidyr::drop_na(any_of(c("by1", "by2")))
             # perform paired cohen's d test
-            withr::with_namespace(
-              package = "effectsize",
-              code = hedges_g(x = data_wide[["by1"]], y = data_wide[["by2"]], paired = TRUE, ci = conf.level, ...)
-            ) |>
+            effectsize::hedges_g(x = data_wide[["by1"]], y = data_wide[["by2"]], paired = TRUE, ci = conf.level, ...) |>
               parameters::standardize_names(style = "broom") |>
               dplyr::mutate(method = "Paired Hedge's G")
           }),
diff --git a/R/cardx-package.R b/R/cardx-package.R
index 9a843b1bf..5e11aba49 100644
--- a/R/cardx-package.R
+++ b/R/cardx-package.R
@@ -7,4 +7,4 @@
 ## usethis namespace: end
 NULL
 
-utils::globalVariables(c(".", "hedges_g"))
+utils::globalVariables(c("."))
diff --git a/man/ard_effectsize_hedges_g.Rd b/man/ard_effectsize_hedges_g.Rd
index 23c43e8d2..60c04f1e8 100644
--- a/man/ard_effectsize_hedges_g.Rd
+++ b/man/ard_effectsize_hedges_g.Rd
@@ -46,7 +46,7 @@ The data are then passed as
 \verb{effectsize::hedges_g(x = data_wide[[<by level 1>]], y = data_wide[[<by level 2>]], paired = TRUE, ...)}.
 }
 \examples{
-\dontshow{if (do.call(asNamespace("cardx")$is_pkg_installed, list(pkg = c("effectsize", "parameters", "withr"), reference_pkg = "cardx"))) (if (getRversion() >= "3.4") withAutoprint else force)(\{ # examplesIf}
+\dontshow{if (do.call(asNamespace("cardx")$is_pkg_installed, list(pkg = c("effectsize", "parameters"), reference_pkg = "cardx"))) (if (getRversion() >= "3.4") withAutoprint else force)(\{ # examplesIf}
 cards::ADSL |>
   dplyr::filter(ARM \%in\% c("Placebo", "Xanomeline High Dose")) |>
   ard_effectsize_hedges_g(by = ARM, variables = AGE)
diff --git a/tests/testthat/test-ard_effectsize_hedges_g.R b/tests/testthat/test-ard_effectsize_hedges_g.R
index 3bd0024e0..b21748c60 100644
--- a/tests/testthat/test-ard_effectsize_hedges_g.R
+++ b/tests/testthat/test-ard_effectsize_hedges_g.R
@@ -1,8 +1,6 @@
-skip_if_not(is_pkg_installed(c("effectsize", "parameters", "withr"), reference_pkg = "cardx"))
+skip_if_not(is_pkg_installed(c("effectsize", "parameters"), reference_pkg = "cardx"))
 
 test_that("ard_effectsize_hedges_g() works", {
-  withr::local_namespace("effectsize")
-
   expect_error(
     ard_hedges_g <-
       cards::ADSL |>
@@ -14,7 +12,7 @@ test_that("ard_effectsize_hedges_g() works", {
   expect_equal(
     ard_hedges_g |>
       cards::get_ard_statistics(stat_name %in% c("estimate", "conf.low", "conf.high")),
-    hedges_g(
+    effectsize::hedges_g(
       AGE ~ ARM,
       data = cards::ADSL |> dplyr::filter(ARM %in% c("Placebo", "Xanomeline High Dose"))
     ) |>
@@ -45,8 +43,6 @@ test_that("ard_effectsize_hedges_g() works", {
 })
 
 test_that("ard_effectsize_paired_hedges_g() works", {
-  withr::local_namespace("effectsize")
-
   ADSL_paired <-
     cards::ADSL[c("ARM", "AGE")] |>
     dplyr::filter(ARM %in% c("Placebo", "Xanomeline High Dose")) |>
@@ -72,7 +68,7 @@ test_that("ard_effectsize_paired_hedges_g() works", {
           by = "USUBJID"
         ),
       expr =
-        hedges_g(
+        effectsize::hedges_g(
           x = AGE1,
           y = AGE2,
           paired = TRUE