Tennis elbow (also known as lateral epicondylitis, lateral epicondalgia, CEO tendinopathy, CEO tendinitis...) is very very common and notoriously difficult to treat! Thankfully, there are some treatment strategies that are demonstrated to work with the majority of cases.

So, what do we need to know about tennis elbow:

It is a TENDON problem. Much the same as achilles tendinopathy (in runners) and patella tendinopathy (in jumping athletes).
The name 'tennis elbow' is actually a bit misleading - as less than 10% of these injuries occur in tennis players.
Most tendon problems do NOT respond to prolonged rest (more on that here)
Tendons, particularly tennis elbow, DO NOT respond to PRP (Platelet Rich Plasma, or blood injections). There are four studies which looked at PRP injections, and all showed no benefit (except one which compared PRP to Cortisone injection, which we know is harmful to tendon tissue!). More on the review of PRP injections for tennis elbow is here
People with chronic tennis elbow often develop weakness in the muscles above and below the elbow. Some great work from Queensland researchers has shown shoulder, wrist and finger muscles can become weak. Unless this is addressed, this may delay recovery. More on weakness in surrounding muscle groups is here
The same researchers found that pain processing can change with chronic tennis elbow, that is, pain can be perceived as worse than it would otherwise because the brain becomes sensitive to the feedback from the elbow.
Not all tendons are the same! Different tennis elbows need different treatment
Stretching rarely helps. Remember, tendons don't stretch and stretching can actually make some of them worse! More on why stretching doesn't help is here

So what do we do to help, if stretching, rest, and blood injections don't help? It's different for different people and situations but here are some considerations

Sometimes, short term anti-inflammatory medications to help with pain. We also use adjunctive medications like green tea, and fish oil in specific instances (see here for more on this)
Treat the tendon! This normally requires relatively heavy and relatively slow exercises to load the tendon and strengthen the surrounding muscles. This treatment isn't exciting, or quick, but it does help most of these tendon injuries
Don't forget the shoulder and wrist! Getting these stronger can offload the elbow in the long term and remember, they are often weaker after having a sore elbow for several months
Occasionally, we using bracing, taping, or shockwave therapy to reduce pain. These by themselves are very rarely solutions - the rehab is generally 80-90% of the battle!
Passive treatments, such as massage, acupunture, dry needling and electrotherapy (ultrasound, laser, interferential) by themselves do not help. They can still be used however always in conjunction with a strength/loading program.
Reassurance and empowering the patient on how to monitor their symptoms (we normally look at pain 24 hours after activity as a good response tool)
Finally relearning new movement patterns can be helpful, as these can be altered on occasion is chronic situations. And of course, addressing the reason why the tennis elbow problem developed in the first place!

Aidan Rich is an APA Sports Physiotherapist with Advance Healthcare in Boronia. He has a special interest in tendon, hip and groin injuries. The clinic services nearby suburbs such as Ringwood East, Bayswater and Ferntree Gully with Sports Physiotherapy.