Many veterans put all their energy into their main service-connected injury and never realize that condition may be quietly causing other problems — problems the VA will also compensate. These are called secondary conditions, and they are one of the most overlooked parts of a disability claim. This guide explains what secondary conditions are, common examples, and how to actually prove the connection.

What Is a Secondary Condition?

A secondary condition is a disability that was caused — or made worse — by a condition that is already service-connected. The original injury is the "primary" condition; anything that develops as a result of it can be claimed as "secondary."

Here is the key point: a secondary condition does not have to trace directly back to your time in service on its own. It only has to be linked to a disability the VA has already recognized as service-connected. That makes secondary claims a powerful way to raise your overall rating.

Common Examples of Secondary Conditions

Secondary conditions tend to show up in patterns the VA sees often. A few common examples:

• Sleep apnea secondary to PTSD, or to weight gain from a service-connected condition.
• Depression or anxiety secondary to chronic pain or a disabling physical injury.
• Knee, hip, or back problems secondary to an altered gait — for example, favoring one leg because of a service-connected ankle or knee injury, which wears down the other joints over time.
• Radiculopathy (nerve pain) secondary to a service-connected back condition.
• Migraines secondary to a head injury or to medication for another service-connected condition.

If you have a service-connected disability and a newer problem that seems to have grown out of it, there may be a secondary claim worth exploring.

Why Secondary Claims Get Denied

Secondary claims get denied for the same reason many claims do: the file does not clearly connect the two conditions. You might have a documented primary disability and a clear new diagnosis, but if nothing in the record explains how one led to the other, the VA has no basis to grant it.

That missing explanation — the medical link between the primary and the secondary condition — is what sinks otherwise valid claims.

How a Nexus Letter Proves the Connection

This is exactly where a nexus letter does its work. (If the term is new to you, here is what a nexus letter is and how it functions.)

For a secondary claim, a strong nexus letter from a qualified provider:

• States that your secondary condition is at least as likely as not caused or aggravated by your service-connected primary condition.
• Explains the medical reasoning behind that connection, not just the conclusion.
• Shows the provider actually reviewed your records rather than signing a template.

The word "aggravated" matters here. Even if your service-connected condition did not cause the secondary problem outright, a claim can be granted if it made an existing condition meaningfully worse.

What You Need to File a Secondary Claim

In general, a secondary claim rests on three pieces:

1. A current diagnosis of the secondary condition.
2. An already service-connected primary condition.
3. A medical link between the two.

You can read more about how the VA handles disability claims on its official site. The first two pieces come from your records; the third is usually where a nexus letter makes the difference.

The Bottom Line

If you have a service-connected disability and have developed another condition that seems related, you may be leaving a rating on the table by not filing a secondary claim. The hurdle is almost always proving the connection — and that is a solvable problem.

2026 Update: The VA updated its secondary service connection causation standard effective May 1, 2026. Nexus letters for secondary claims must now satisfy a "but for" causation standard — see The VA Changed the Rules on Secondary Claims: What the New ‘But For’ Standard Means for Your Nexus Letter (2026) for what this means for your claim.

If you would like help establishing that link, you can see how our process works or reach out to talk through your situation.