diff --git a/CHANGELOG.md b/CHANGELOG.md
index 285301a1d8..369fe04708 100644
--- a/CHANGELOG.md
+++ b/CHANGELOG.md
@@ -17,6 +17,7 @@
     Bug #5415: Environment maps in ebony cuirass and HiRez Armors Indoril cuirass don't work
     Bug #5416: Junk non-node records before the root node are not handled gracefully
     Bug #5424: Creatures do not headtrack player
+    Bug #5425: Poison effect only appears for one frame
     Bug #5427: GetDistance unknown ID error is misleading
     Feature #5362: Show the soul gems' trapped soul in count dialog
 
diff --git a/apps/openmw/mwgui/widgets.cpp b/apps/openmw/mwgui/widgets.cpp
index 0568efeb45..74076641a9 100644
--- a/apps/openmw/mwgui/widgets.cpp
+++ b/apps/openmw/mwgui/widgets.cpp
@@ -443,6 +443,9 @@ namespace MWGui
             // constant effects have no duration and no target
             if (!mEffectParams.mIsConstant)
             {
+                if (!(magicEffect->mData.mFlags & ESM::MagicEffect::AppliedOnce))
+                    mEffectParams.mDuration = std::max(1, mEffectParams.mDuration);
+
                 if (mEffectParams.mDuration > 0 && !(magicEffect->mData.mFlags & ESM::MagicEffect::NoDuration))
                 {
                     spellLine += " " + MWBase::Environment::get().getWindowManager()->getGameSettingString("sfor", "") + " " + MyGUI::utility::toString(mEffectParams.mDuration) + ((mEffectParams.mDuration == 1) ? sec : secs);
diff --git a/apps/openmw/mwmechanics/autocalcspell.cpp b/apps/openmw/mwmechanics/autocalcspell.cpp
index 6d30909180..9cee1aa318 100644
--- a/apps/openmw/mwmechanics/autocalcspell.cpp
+++ b/apps/openmw/mwmechanics/autocalcspell.cpp
@@ -262,6 +262,8 @@ namespace MWMechanics
             int duration = 0;
             if (!(magicEffect->mData.mFlags & ESM::MagicEffect::NoDuration))
                 duration = effect.mDuration;
+            if (!(magicEffect->mData.mFlags & ESM::MagicEffect::AppliedOnce))
+                duration = std::max(1, duration);
 
             static const float fEffectCostMult = MWBase::Environment::get().getWorld()->getStore()
                 .get<ESM::GameSetting>().find("fEffectCostMult")->mValue.getFloat();
diff --git a/apps/openmw/mwmechanics/spellcasting.cpp b/apps/openmw/mwmechanics/spellcasting.cpp
index 7699349860..7aec5d4716 100644
--- a/apps/openmw/mwmechanics/spellcasting.cpp
+++ b/apps/openmw/mwmechanics/spellcasting.cpp
@@ -208,10 +208,15 @@ namespace MWMechanics
                     }
 
                     bool hasDuration = !(magicEffect->mData.mFlags & ESM::MagicEffect::NoDuration);
-                    if (hasDuration && effectIt->mDuration == 0)
+                    effect.mDuration = hasDuration ? static_cast<float>(effectIt->mDuration) : 1.f;
+
+                    bool appliedOnce = magicEffect->mData.mFlags & ESM::MagicEffect::AppliedOnce;
+                    if (!appliedOnce)
+                        effect.mDuration = std::max(1.f, effect.mDuration);
+
+                    if (effect.mDuration == 0)
                     {
                         // We still should add effect to list to allow GetSpellEffects to detect this spell
-                        effect.mDuration = 0.f;
                         appliedLastingEffects.push_back(effect);
 
                         // duration 0 means apply full magnitude instantly
@@ -224,8 +229,6 @@ namespace MWMechanics
                     }
                     else
                     {
-                        effect.mDuration = hasDuration ? static_cast<float>(effectIt->mDuration) : 1.f;
-
                         effect.mTimeLeft = effect.mDuration;
 
                         targetEffects.add(MWMechanics::EffectKey(*effectIt), MWMechanics::EffectParam(effect.mMagnitude));
diff --git a/apps/openmw/mwmechanics/spellpriority.cpp b/apps/openmw/mwmechanics/spellpriority.cpp
index 9428beafc0..81658193d6 100644
--- a/apps/openmw/mwmechanics/spellpriority.cpp
+++ b/apps/openmw/mwmechanics/spellpriority.cpp
@@ -394,8 +394,9 @@ namespace MWMechanics
                     priority = 10;
                 const MWMechanics::CreatureStats& stats = actor.getClass().getCreatureStats(actor);
                 const DynamicStat<float>& current = stats.getDynamic(effect.mEffectID - ESM::MagicEffect::RestoreHealth);
+                // NB: this currently assumes the hardcoded magic effect flags are used
                 const float magnitude = (effect.mMagnMin + effect.mMagnMax)/2.f;
-                const float toHeal = magnitude * effect.mDuration;
+                const float toHeal = magnitude * std::max(1, effect.mDuration);
                 // Effect doesn't heal more than we need, *or* we are below 1/2 health
                 if (current.getModified() - current.getCurrent() > toHeal
                         || current.getCurrent() < current.getModified()*0.5)
diff --git a/apps/openmw/mwmechanics/spellutil.cpp b/apps/openmw/mwmechanics/spellutil.cpp
index def3bbbc84..bb4953e482 100644
--- a/apps/openmw/mwmechanics/spellutil.cpp
+++ b/apps/openmw/mwmechanics/spellutil.cpp
@@ -31,9 +31,12 @@ namespace MWMechanics
             magicEffect = store.get<ESM::MagicEffect>().find(effect.mEffectID);
         bool hasMagnitude = !(magicEffect->mData.mFlags & ESM::MagicEffect::NoMagnitude);
         bool hasDuration = !(magicEffect->mData.mFlags & ESM::MagicEffect::NoDuration);
+        bool appliedOnce = magicEffect->mData.mFlags & ESM::MagicEffect::AppliedOnce;
         int minMagn = hasMagnitude ? effect.mMagnMin : 1;
         int maxMagn = hasMagnitude ? effect.mMagnMax : 1;
         int duration = hasDuration ? effect.mDuration : 1;
+        if (!appliedOnce)
+            duration = std::max(1, duration);
         static const float fEffectCostMult = store.get<ESM::GameSetting>().find("fEffectCostMult")->mValue.getFloat();
 
         float x = 0.5 * (std::max(1, minMagn) + std::max(1, maxMagn));