Secondary condition nexus letters
A secondary claim connects a new condition to one the VA has already service-connected. You don't have to re-prove your in-service event — you just need a well-reasoned nexus letter explaining the medical link. It's often the shortest path to a higher combined rating.
The basics
What is a secondary service-connected condition?
A secondary service-connected condition is a medical or mental health condition that is caused by, the result of, or aggravated by a disability the VA already recognizes as service-connected. The VA evaluates these claims under 38 CFR 3.310.
The key advantage is what you don't have to prove. In a direct claim, you have to establish that something happened in service and connect your condition to it. In a secondary claim, that in-service link is already settled — the VA has granted the primary condition. The only question left is medical: does your service-connected condition cause or worsen the new one? That's the question a secondary nexus letter answers.
Two ways a secondary claim can be established: the service-connected condition directly caused the new condition, or it aggravated a condition beyond its natural progression. A strong nexus letter addresses both theories separately, because a claim can succeed on aggravation even where causation is uncertain.
Why it matters
Why file a secondary claim?
For many veterans, a secondary claim is the most efficient way to raise their overall benefits. Because the in-service event is already established, these claims can turn on a single medical question — and each condition the VA adds contributes to your combined disability rating.
The VA doesn't simply add percentages; it uses a combined ratings table. But adding a well-supported secondary condition can still move your combined rating into a higher bracket, and in some cases contributes toward a 100% or TDIU evaluation. If you are already service-connected for a condition but believe it's rated too low, that's a separate path — see rating increases.
- No new in-service stressor or event to prove
- Turns on a focused medical question the records can answer
- Each granted condition can raise your combined rating
- Can address both causation and aggravation
How they connect
Which direction does your claim run?
Secondary claims run in both directions, and Dr. Allen — a psychiatrist and former VA C&P examiner — writes opinions for both, because the mind and body drive each other.
Physical conditions secondary to mental health
PTSD, depression, and anxiety affect sleep, weight, blood pressure, inflammation, and medication use — which can cause or worsen physical conditions, including:
- Obstructive sleep apnea
- Hypertension (high blood pressure)
- GERD and irritable bowel syndrome
- Migraine and tension headaches
- Erectile dysfunction
- Bruxism / TMJ dysfunction
- Type 2 diabetes and weight gain as an intermediate step
- Fibromyalgia
Mental health secondary to physical conditions
Service-connected physical conditions cause chronic pain, sleep loss, fatigue, and lost independence — which can cause or worsen mental health conditions, including:
- Depression secondary to chronic pain
- Anxiety secondary to a service-connected condition
- Insomnia secondary to tinnitus
- Depression or anxiety secondary to tinnitus or hearing loss
- Mood changes secondary to traumatic brain injury
- Depression secondary to sleep apnea, migraines, or GI conditions
Conditions we cover
Secondary conditions we write nexus letters for
Each of these has its own page explaining the medical mechanism and what the VA looks for. Start with the one closest to your claim.
Sleep apnea secondary to PTSD
Hyperarousal, disrupted sleep, medication effects, and weight gain can contribute to obstructive sleep apnea.
Learn moreHypertension secondary to PTSD
Chronic sympathetic activation from PTSD can raise and sustain blood pressure over time.
Learn moreGERD & IBS secondary to PTSD
Stress physiology and psychiatric medications can drive reflux and irritable bowel symptoms.
Learn moreMigraine & headache nexus
Headache disorders frequently travel with PTSD, depression, and tinnitus.
Learn moreDepression secondary to chronic pain
Service-connected pain, lost mobility, and disrupted sleep can cause or worsen depression.
Learn moreUrinary frequency secondary to PTSD
Hyperarousal, disrupted sleep, and psychiatric medications can drive urinary frequency and urgency.
Learn moreHemorrhoids secondary to pain medication
Opioids and other pain medications for a service-connected condition can cause or worsen hemorrhoids.
Learn moreType 2 diabetes secondary to antipsychotic medication
Second-generation antipsychotics prescribed for a service-connected mental health condition carry an FDA class warning for hyperglycemia and diabetes.
Learn moreSee all nexus letters
The full directory of every condition and letter type Brightview writes, including ED, fibromyalgia, diabetes, and TMJ.
View the directoryWhat works
What makes a secondary nexus letter strong?
Many secondary claims are denied not because the connection isn't real, but because the letter didn't prove it the way VA raters require. A well-built secondary opinion:
- Names the diagnosis and the specific service-connected condition it's tied to
- Explains the medical mechanism, not just a conclusion
- Addresses the symptom timeline and onset relative to the primary condition
- Applies the “at least as likely as not” standard under 38 CFR 3.310
- Separates causation and aggravation as independent theories
- Considers alternative causes so it isn't dismissed as speculative
If your secondary claim was already denied — often because the examiner blamed a risk factor like obesity or never addressed aggravation — a rebuttal review can respond to the VA's specific reasoning.
Who writes it
Who writes your opinion?
Every opinion is written by Dr. Jessica Allen, a licensed psychiatrist and former VA Compensation & Pension examiner. Having sat in the examiner's chair, she knows how the VA weighs a secondary opinion from the inside — and, as a former C&P examiner, she is well versed in the governing regulations (Title 38 CFR) and the VA's M21-1 Adjudication Procedures Manual that raters actually apply. That means each letter is written with the medico-legal wording a nexus opinion needs to be persuasive, grounded in your records, with no templates and no ghostwriting. For the underlying mental health claim, see PTSD & MST nexus letters.
Common questions
Secondary service connection questions
Not sure which condition connects to your claim?
Tell Dr. Allen what you're already service-connected for, and she'll tell you honestly whether a secondary nexus letter fits. The consultation is free, with no obligation.
Jessica Allen, M.D. — licensed psychiatrist and former VA C&P examiner. Secondary-condition nexus letters for veterans in all 50 states.
This document is educational and general in nature and is not medical or legal advice. Brightview Psychiatry Solutions provides medical opinions only and does not file VA claims or provide legal representation, and no VA outcome is guaranteed. For questions about appeals, deadlines, or claim strategy, consult a VA-accredited attorney, claims agent, or VSO.