diff --git a/res/css/views/elements/_Tooltip.scss b/res/css/views/elements/_Tooltip.scss
index efaaf83545..7efea2c3f7 100644
--- a/res/css/views/elements/_Tooltip.scss
+++ b/res/css/views/elements/_Tooltip.scss
@@ -76,9 +76,6 @@ limitations under the License.
 }
 
 .mx_Tooltip_timeline {
-    margin-left: -42px;
-    margin-top: -42px;
-
     &.mx_Tooltip {
         background-color: $inverted-bg-color;
         color: $accent-fg-color;
diff --git a/src/components/views/elements/AccessibleTooltipButton.tsx b/src/components/views/elements/AccessibleTooltipButton.tsx
index 45e769e32d..f4d63136e1 100644
--- a/src/components/views/elements/AccessibleTooltipButton.tsx
+++ b/src/components/views/elements/AccessibleTooltipButton.tsx
@@ -24,7 +24,6 @@ import Tooltip from './Tooltip';
 
 interface ITooltipProps extends IProps {
     title: string;
-    tooltip?: React.ReactNode;
     tooltipClassName?: string;
 }
 
@@ -53,7 +52,7 @@ export default class AccessibleTooltipButton extends React.PureComponent<IToolti
     };
 
     render() {
-        const {title, children, tooltip, ...props} = this.props;
+        const {title, children, ...props} = this.props;
         const tooltipClassName = classnames(
             "mx_AccessibleTooltipButton_tooltip",
             this.props.tooltipClassName,
@@ -62,7 +61,7 @@ export default class AccessibleTooltipButton extends React.PureComponent<IToolti
         const tip = this.state.hover ? <Tooltip
             className="mx_AccessibleTooltipButton_container"
             tooltipClassName={tooltipClassName}
-            label={tooltip || title}
+            label={title}
         /> : <div />;
         return (
             <AccessibleButton {...props} onMouseOver={this.onMouseOver} onMouseOut={this.onMouseOut} aria-label={title}>
diff --git a/src/components/views/messages/ReactionsRowButton.js b/src/components/views/messages/ReactionsRowButton.js
index 8c0cf3b0b0..09824cd315 100644
--- a/src/components/views/messages/ReactionsRowButton.js
+++ b/src/components/views/messages/ReactionsRowButton.js
@@ -19,11 +19,10 @@ import PropTypes from 'prop-types';
 import classNames from 'classnames';
 
 import {MatrixClientPeg} from '../../../MatrixClientPeg';
+import * as sdk from '../../../index';
 import { _t } from '../../../languageHandler';
 import { formatCommaSeparatedList } from '../../../utils/FormattingUtils';
 import dis from "../../../dispatcher/dispatcher";
-import AccessibleTooltipButton from "../elements/AccessibleTooltipButton";
-import {unicodeToShortcode} from "../../../HtmlUtils";
 
 export default class ReactionsRowButton extends React.PureComponent {
     static propTypes = {
@@ -39,6 +38,14 @@ export default class ReactionsRowButton extends React.PureComponent {
         myReactionEvent: PropTypes.object,
     }
 
+    constructor(props) {
+        super(props);
+
+        this.state = {
+            tooltipVisible: false,
+        };
+    }
+
     onClick = (ev) => {
         const { mxEvent, myReactionEvent, content } = this.props;
         if (myReactionEvent) {
@@ -58,7 +65,24 @@ export default class ReactionsRowButton extends React.PureComponent {
         }
     };
 
+    onMouseOver = () => {
+        this.setState({
+            // To avoid littering the DOM with a tooltip for every reaction,
+            // only render it on first use.
+            tooltipRendered: true,
+            tooltipVisible: true,
+        });
+    }
+
+    onMouseOut = () => {
+        this.setState({
+            tooltipVisible: false,
+        });
+    }
+
     render() {
+        const ReactionsRowButtonTooltip =
+            sdk.getComponent('messages.ReactionsRowButtonTooltip');
         const { mxEvent, content, count, reactionEvents, myReactionEvent } = this.props;
 
         const classes = classNames({
@@ -66,9 +90,18 @@ export default class ReactionsRowButton extends React.PureComponent {
             mx_ReactionsRowButton_selected: !!myReactionEvent,
         });
 
+        let tooltip;
+        if (this.state.tooltipRendered) {
+            tooltip = <ReactionsRowButtonTooltip
+                mxEvent={this.props.mxEvent}
+                content={content}
+                reactionEvents={reactionEvents}
+                visible={this.state.tooltipVisible}
+            />;
+        }
+
         const room = MatrixClientPeg.get().getRoom(mxEvent.getRoomId());
         let label;
-        let tooltip;
         if (room) {
             const senders = [];
             for (const reactionEvent of reactionEvents) {
@@ -93,37 +126,14 @@ export default class ReactionsRowButton extends React.PureComponent {
                     },
                 },
             );
-
-            const shortName = unicodeToShortcode(content);
-            tooltip = <div>{_t(
-                "<reactors/><reactedWith>reacted with %(shortName)s</reactedWith>",
-                {
-                    shortName,
-                },
-                {
-                    reactors: () => {
-                        return <div className="mx_ReactionsRowButtonTooltip_senders">
-                            {formatCommaSeparatedList(senders, 6)}
-                        </div>;
-                    },
-                    reactedWith: (sub) => {
-                        if (!shortName) {
-                            return null;
-                        }
-                        return <div className="mx_ReactionsRowButtonTooltip_reactedWith">
-                            {sub}
-                        </div>;
-                    },
-                },
-            )}</div>;
         }
 
-        return <AccessibleTooltipButton
-            className={classes}
+        const AccessibleButton = sdk.getComponent('elements.AccessibleButton');
+        return <AccessibleButton className={classes}
+            aria-label={label}
             onClick={this.onClick}
-            title={label}
-            tooltip={tooltip}
-            tooltipClassName="mx_Tooltip_timeline"
+            onMouseOver={this.onMouseOver}
+            onMouseOut={this.onMouseOut}
         >
             <span className="mx_ReactionsRowButton_content" aria-hidden="true">
                 {content}
@@ -131,6 +141,7 @@ export default class ReactionsRowButton extends React.PureComponent {
             <span className="mx_ReactionsRowButton_count" aria-hidden="true">
                 {count}
             </span>
-        </AccessibleTooltipButton>;
+            {tooltip}
+        </AccessibleButton>;
     }
 }
diff --git a/src/components/views/messages/ReactionsRowButtonTooltip.js b/src/components/views/messages/ReactionsRowButtonTooltip.js
new file mode 100644
index 0000000000..59e9d2ad7f
--- /dev/null
+++ b/src/components/views/messages/ReactionsRowButtonTooltip.js
@@ -0,0 +1,85 @@
+/*
+Copyright 2019 The Matrix.org Foundation C.I.C.
+
+Licensed under the Apache License, Version 2.0 (the "License");
+you may not use this file except in compliance with the License.
+You may obtain a copy of the License at
+
+    http://www.apache.org/licenses/LICENSE-2.0
+
+Unless required by applicable law or agreed to in writing, software
+distributed under the License is distributed on an "AS IS" BASIS,
+WITHOUT WARRANTIES OR CONDITIONS OF ANY KIND, either express or implied.
+See the License for the specific language governing permissions and
+limitations under the License.
+*/
+
+import React from 'react';
+import PropTypes from 'prop-types';
+
+import {MatrixClientPeg} from '../../../MatrixClientPeg';
+import * as sdk from '../../../index';
+import { unicodeToShortcode } from '../../../HtmlUtils';
+import { _t } from '../../../languageHandler';
+import { formatCommaSeparatedList } from '../../../utils/FormattingUtils';
+
+export default class ReactionsRowButtonTooltip extends React.PureComponent {
+    static propTypes = {
+        // The event we're displaying reactions for
+        mxEvent: PropTypes.object.isRequired,
+        // The reaction content / key / emoji
+        content: PropTypes.string.isRequired,
+        // A Set of Martix reaction events for this key
+        reactionEvents: PropTypes.object.isRequired,
+        visible: PropTypes.bool.isRequired,
+    }
+
+    render() {
+        const Tooltip = sdk.getComponent('elements.Tooltip');
+        const { content, reactionEvents, mxEvent, visible } = this.props;
+
+        const room = MatrixClientPeg.get().getRoom(mxEvent.getRoomId());
+        let tooltipLabel;
+        if (room) {
+            const senders = [];
+            for (const reactionEvent of reactionEvents) {
+                const member = room.getMember(reactionEvent.getSender());
+                const name = member ? member.name : reactionEvent.getSender();
+                senders.push(name);
+            }
+            const shortName = unicodeToShortcode(content);
+            tooltipLabel = <div>{_t(
+                "<reactors/><reactedWith>reacted with %(shortName)s</reactedWith>",
+                {
+                    shortName,
+                },
+                {
+                    reactors: () => {
+                        return <div className="mx_ReactionsRowButtonTooltip_senders">
+                            {formatCommaSeparatedList(senders, 6)}
+                        </div>;
+                    },
+                    reactedWith: (sub) => {
+                        if (!shortName) {
+                            return null;
+                        }
+                        return <div className="mx_ReactionsRowButtonTooltip_reactedWith">
+                            {sub}
+                        </div>;
+                    },
+                },
+            )}</div>;
+        }
+
+        let tooltip;
+        if (tooltipLabel) {
+            tooltip = <Tooltip
+                tooltipClassName="mx_Tooltip_timeline"
+                visible={visible}
+                label={tooltipLabel}
+            />;
+        }
+
+        return tooltip;
+    }
+}