Its too early to judge but according to current data available (still at early stage) advise that you shouldn't use hashtags on Facebook. 

Hashtags on Facebook have only been around since June 2013. Three months later, research from EdgeRank Checker found that using hashtags on Facebook has zero positive effect on reach. Posts without hashtags outperform those with hashtags.

This data, courtesy of Buddy Media, is one of the most-cited examples of the effectiveness of hashtags. 
Increasing your social media presence and online engagement, is one of the most important factors in social media management. 

Buddy Media’s research shows that using one or two hashtags should be the max in tweeting. 


When you use more than two hashtags, your engagement actually drops by an average of 17 percent as the table below presents. 

Twitter’s own research into hashtags confirms that there is significant advantage in using hashtags as well.  

Individuals can see a 100 percent increase in engagement by using hashtags (the same bump as seen in the Buddy Media study). Brands can see a 50 percent increase.

Engagement, as measured in these studies, can include clicks, retweets, favorites, and replies, yet if it’s only retweets your after, hashtags still would be a smart bet.

Most major social media platforms support hashtags. These include:

Twitter: Twitter is the birthplace of modern hashtag usage — as such, its hashtags are more versatile than other sites' (see “Tone & Voice,” below). Twitter hashtags are mainly used to denote specific topics of conversation; the “Trends” sidebar of your Twitter feed curates a list of hashtags you might be interested in, based on your tweets.

When you search for a hashtag on Twitter, there are three ways to filter the results. The "Top" option displays the most relevant and popular posts, including those from users you don't follow. "All" shows you every tweet that uses the specific hashtag in real time, and "People you follow" will only display results from users you are following.

Facebook: Facebook only recently added hashtag support in June 2013, and the practice has not picked up much steam. Nevertheless, clicking on Facebook hashtags will take you to a list of posts containing the same hashtag. The results are not limited to people you know.

Instagram: Hashtags can be used to complement photos shared on Instagram and help you discover new accounts and pick up followers. Some hashtags were created specifically for Instagram photo challenges — #ThrowbackThursday, for example, encourages users to post retro photos. Vine uses hashtags in the same way — try accompanying each of your Vine videos with at least one hashtag to maximize shareability. 

Google+: When you click on a hashtag in Google+, the search results will include the original hashtag as well as posts with similar tags and keywords. Google search results display on the left side of the page, while hashtag results from within Google+ appear on the right. Google also gives you the option to search within Facebook or Twitter.

Tumblr: Tumblr posts have a special “Tag” section where you can enter tags. These tags function like Twitter hashtags, organizing posts by topic, but the hash symbol is inserted automatically. Hashtags included in the main body of a post are not transformed into links.

Pinterest: Use Pinterest hashtags to mark and search for content. Click on the hashtag in a pin description to navigate results that contain the exact hashtag, plus pins with the same word or phrase in the description.

Curious which hashtags are trending across social media? We prefer to use Hashtags.org which gives us information on which hashtags are hot in real time (and which ones of course, you better have to avoid).

If you’re social media addicted (like we), hashtags — those short links preceded by the pound sign (#) in front, may seem confusing and unnecessary. Hashtags, are integral to the way we communicate online, and it’s important to know how to use them (even though some people, like Jimmy Fallon and Justin Timberlake, are not the biggest fans). Plus, they can be a lot of fun.

On Twitter, the pound sign (or hash) turns any word or group of words that directly follow it into a searchable link. This allows you to organize content and track discussion related topics based on those keywords. So, if you wanted to post about the Breaking Bad finale, you would include #BreakingBad in your tweet to join the conversation. Click on a hashtag to see all the posts that mention the subject in real time.

The hashtag’s widespread use began with Twitter but has extended to other social media platforms. In 2007, developer Chris Messina proposed, in a tweet, that Twitter begin grouping topics using the hash symbol. Twitter initially rejected the idea. But in October 2007, citizen journalists began using the hashtag #SanDiegoFire, at Messina’s suggestion, to tweet updates on a series of forest fires in San Diego. The practice of hashtagging took off; now users and brands employ hashtags to cover serious political events (#Cairo) and entertainment topics (#MileyCyrus) alike.

As such #hashtags have turned out to be a very popular and dynamic tool in communicating "direct" and relevant content to the people that have the same and / or related level of interest. 

Which characters can you include in a #hashtag?

For starters, spaces are an absolute no-no. Even if your hashtag contains multiple words, group them all together. If you want to differentiate between words, use capitals instead (#BlueJasmine). Uppercase letters will not alter your search results, so searching for #BlueJasmine will yield the same results as #bluejasmine.

Numbers are supported, so tweet about #50ShadesOfGrey to your heart’s content. However, punctuation marks are not, so commas, periods, exclamation points, question marks and apostrophes are out. Forget about asterisks, ampersands or any other special characters.

Keep in mind that the @ symbol does something completely different. Using @ before a person’s Twitter handle will tweet at him directly, letting him know you have written to him via the @Connect tab. A hashtag will not. Sometimes users will hashtag a celebrity’s name instead of using her Twitter handle — it is acceptable to tweet #Lorde or @lordemusic. But if you are trying to reach someone directly, don’t use a hashtag.

There is no preset list of hashtags. Create a brand new hashtag simply by putting the hash before a series of words, and if it hasn't been used before, voilà! You've invented a hashtag.

Many major brands now have Twitter accounts, and some choose to create hashtags to promote specific events or campaigns. If you want to use Twitter as part of your business strategy, here are a few tips to keep in mind:

Consolidate your tweets: Choose a specific account that will represent your brand or business. Set up a business account, or designate one employee to tweet on behalf of the company. That way, users can find all of your tweets in one place.

Use relevant hashtags: See what hashtags other businesses in your field are using. If you’re promoting cheap airfare, you will want to use hashtags like #CheapTravel and #FlightDeals so users will find you when they search for those keywords.

Follow trends: See what hashtags are trending and make use of them — if they are relevant to your business. Using a popular hashtag that has nothing to do with your brand (for example, including #MileyCyrus in a tweet about cheap airfare) makes you look like a spammer and will hurt your credibility.

Create your own hashtag: If you want to create a special hashtag for an event or campaign, select one that hasn't been used before and remind everyone to use it in related tweets. Be sure to include the hashtag in any promotional materials. Make it informative but short — for example, Mashable uses #MashReads to talk about writers who visit our HQ.

Generate buzz: Creating a contest, raffle or promotion is a great way to get Twitter talking about your brand. Users will be more likely to retweet your hashtags if they know they might win a prize by doing so. For instance, if you're promoting a new confectionery shop called Candy Land, get Twitter buzzing by offering free treats to users who tweet #CandyLandPromo.

Remember, your hashtag’s visibility will depend on your privacy settings. If your Twitter account is private, only those authorized to see your tweets will have access to your hashtags. If you are using hashtags to increase your brand's exposure, make sure your tweets are set to Public.