diff --git a/src/view/com/composer/TagInput/index.tsx b/src/view/com/composer/TagInput/index.tsx
index a01b94152c..d3d1f50826 100644
--- a/src/view/com/composer/TagInput/index.tsx
+++ b/src/view/com/composer/TagInput/index.tsx
@@ -23,7 +23,7 @@ import {useStores} from 'state/index'
 import {ActivityIndicator} from 'react-native'
 import {TagInputEntryButton} from './TagInputEntryButton'
 import {uniq} from 'lib/strings/helpers'
-import {sanitizeHashtag} from './util'
+import {sanitizeHashtag, sanitizeHashtagOnChange} from './util'
 
 export function TagInput({
   max = 8,
@@ -103,12 +103,14 @@ export function TagInput({
   )
 
   const onChangeText = React.useCallback(
-    async (v: string) => {
-      setValue(v)
+    async (value: string) => {
+      const tag = sanitizeHashtagOnChange(value)
 
-      if (v.length > 0) {
+      setValue(tag)
+
+      if (tag.length > 0) {
         model.setActive(true)
-        await model.search(v)
+        await model.search(tag)
 
         setSuggestions(model.suggestions)
       } else {
diff --git a/src/view/com/composer/TagInput/index.web.tsx b/src/view/com/composer/TagInput/index.web.tsx
index d0ac8d2c75..2a9a95f1f7 100644
--- a/src/view/com/composer/TagInput/index.web.tsx
+++ b/src/view/com/composer/TagInput/index.web.tsx
@@ -23,7 +23,7 @@ import {useStores} from 'state/index'
 import {TagInputEntryButton} from './TagInputEntryButton'
 import {TextInputFocusEventData} from 'react-native'
 import {uniq} from 'lib/strings/helpers'
-import {sanitizeHashtag} from './util'
+import {sanitizeHashtag, sanitizeHashtagOnChange} from './util'
 
 export function TagInput({
   max = 8,
@@ -153,12 +153,14 @@ export function TagInput({
   )
 
   const onChangeText = React.useCallback(
-    async (v: string) => {
-      setValue(v)
+    async (value: string) => {
+      const tag = sanitizeHashtagOnChange(value)
 
-      if (v.length > 0) {
+      setValue(tag)
+
+      if (tag.length > 0) {
         model.setActive(true)
-        await model.search(v)
+        await model.search(tag)
 
         setDropdownItems(
           model.suggestions.map(item => ({
@@ -199,9 +201,10 @@ export function TagInput({
         (!target || !target.id.includes('tag_autocomplete_option'))
       ) {
         setOpen(false)
+        setValue('')
       }
     },
-    [tags, setOpen],
+    [tags, setOpen, setValue],
   )
 
   React.useEffect(() => {
diff --git a/src/view/com/composer/TagInput/util.ts b/src/view/com/composer/TagInput/util.ts
index b085054853..7abab04f0e 100644
--- a/src/view/com/composer/TagInput/util.ts
+++ b/src/view/com/composer/TagInput/util.ts
@@ -1,8 +1,28 @@
-import {TRAILING_PUNCTUATION_REGEX, LEADING_HASH_REGEX} from '@atproto/api'
+import {
+  HASHTAG_INVALID_CHARACTER_REGEX,
+  TRAILING_PUNCTUATION_REGEX,
+  LEADING_PUNCTUATION_REGEX,
+  LEADING_NUMBER_REGEX,
+} from '@atproto/api'
 
-export function sanitizeHashtag(tagString: string) {
-  return tagString
-    .trim()
-    .replace(LEADING_HASH_REGEX, '')
+/**
+ * Trims leading numbers, all invalid characters, and any trailing punctuation.
+ */
+export function sanitizeHashtag(hashtag: string) {
+  return hashtag
+    .replace(LEADING_PUNCTUATION_REGEX, '')
+    .replace(LEADING_NUMBER_REGEX, '')
+    .replace(HASHTAG_INVALID_CHARACTER_REGEX, '')
     .replace(TRAILING_PUNCTUATION_REGEX, '')
 }
+
+/**
+ * Trims leading numbers and all invalid charactes, but ignores trailing
+ * punctuation in case the user intends to use `_` or `-`.
+ */
+export function sanitizeHashtagOnChange(hashtag: string) {
+  return hashtag
+    .replace(LEADING_PUNCTUATION_REGEX, '')
+    .replace(LEADING_NUMBER_REGEX, '')
+    .replace(HASHTAG_INVALID_CHARACTER_REGEX, '')
+}
diff --git a/src/view/com/composer/text-input/mobile/TagsAutocomplete.tsx b/src/view/com/composer/text-input/mobile/TagsAutocomplete.tsx
index 816e9509ea..a5d6756da5 100644
--- a/src/view/com/composer/text-input/mobile/TagsAutocomplete.tsx
+++ b/src/view/com/composer/text-input/mobile/TagsAutocomplete.tsx
@@ -29,7 +29,9 @@ export function getHashtagAt(text: string, position: number) {
    * show autocomplete after a single # is typed
    * AND the cursor is next to the #
    */
-  for (const match of Array.from(text.matchAll(LEADING_HASH_REGEX))) {
+  for (const match of Array.from(
+    text.matchAll(new RegExp(LEADING_HASH_REGEX, 'g')),
+  )) {
     const {index} = match
     if (index === undefined) continue
     if (position >= index && position <= index + 1) {