hEDS vs. HSD: What's the Difference and Why It Matters for Treatment

If you have been told you are "hypermobile" but left the doctor's office confused about whether you have hypermobile Ehlers-Danlos Syndrome (hEDS) or Hypermobility Spectrum Disorder (HSD), you are not alone. These two diagnoses describe overlapping conditions that exist on the same biological continuum — yet the distinction between them has real consequences for how you are treated, what your insurance will cover, and how your condition is documented in the medical record.

The Core Distinction

Both hEDS and HSD involve generalized joint hypermobility (GJH) — joints that move beyond the normal range of motion due to differences in connective tissue. The fundamental difference is one of diagnostic specificity, not severity.

Hypermobile EDS (hEDS) is diagnosed using the 2017 International Classification criteria, which require all three of the following:

1. Generalized joint hypermobility (Beighton score ≥5, or ≥4 in adults over 50)
2. Two or more features from a list of systemic manifestations (musculoskeletal complications, family history, and/or skin/tissue features)
3. Absence of an alternative diagnosis that better explains the findings

Hypermobility Spectrum Disorder (HSD) is the umbrella term for symptomatic hypermobility that does not meet the full hEDS criteria. HSD is not a lesser diagnosis — it simply means the criteria for hEDS were not fully met, while the patient still has clinically significant hypermobility-related symptoms.

Why the Distinction Matters Clinically

Insurance and Documentation

hEDS has a specific ICD-10 code (Q79.6) that is recognized by most major insurers for physical therapy, occupational therapy, and specialist referrals. HSD uses M35.7, which is newer and less consistently recognized. Some patients find that an hEDS diagnosis opens doors to coverage that an HSD diagnosis does not — though this varies significantly by insurer and country.

Access to Specialists

Many connective tissue disorder clinics and EDS specialists organize their intake criteria around the 2017 hEDS classification. Patients with HSD sometimes report being told they "don't have EDS" and being discharged without a clear treatment pathway, even when their functional impairment is identical to patients who meet the hEDS threshold.

Research and Clinical Trials

Clinical trials for hEDS-specific interventions often use the 2017 criteria as inclusion criteria. Patients with HSD may be excluded from trials even when their biology is essentially the same. This is a recognized limitation of the current classification system that researchers are actively working to address.

Psychological Impact

The diagnostic label matters to patients. Many people with HSD report feeling invalidated — as if their symptoms are "not real enough" for a formal diagnosis. This is clinically harmful. The 2017 criteria explicitly state that HSD is not a lesser condition, and the Ehlers-Danlos Society has published guidance emphasizing that HSD patients deserve the same level of clinical attention and treatment access as hEDS patients.

The Severity Overlap Problem

One of the most important things to understand is that HSD can be more functionally disabling than hEDS in individual cases. The criteria are about diagnostic specificity, not about how much a person suffers. A patient with HSD who has severe joint instability, dysautonomia, chronic pain, and significant disability may have a harder daily life than a patient who technically meets hEDS criteria but has mild symptoms.

This is why many connective tissue specialists now speak of the "hEDS/HSD spectrum" rather than treating them as categorically different diseases.

The MCAS and Dysautonomia Connection

Both hEDS and HSD are strongly associated with mast cell activation syndrome (MCAS) and dysautonomia/POTS. This triad — hypermobility, MCAS, and dysautonomia — is now recognized as a common clinical pattern, though the underlying mechanism is not yet fully understood. Some researchers hypothesize that connective tissue differences in the autonomic nervous system and mast cell-rich tissues may explain the clustering.

If you have been diagnosed with hEDS or HSD, it is worth asking your doctor whether you should be evaluated for POTS (tilt table test or NASA lean test) and MCAS (serum tryptase, 24-hour urine prostaglandins, and a clinical symptom review).

What to Do If You Have an HSD Diagnosis

1. Do not accept "you don't have EDS" as a complete answer. HSD is a legitimate diagnosis with the same treatment approach as hEDS.
2. Ask for a referral to a physical therapist with connective tissue disorder experience. Proprioceptive retraining, joint stabilization exercises, and bracing are the cornerstones of treatment for both conditions.
3. Document your symptoms thoroughly. If your functional impairment is significant, detailed documentation supports insurance appeals and disability applications.
4. Consider a second opinion from an EDS specialist. The 2017 criteria require clinical judgment, and different clinicians apply them differently. Some patients who were told they have HSD are reclassified as hEDS by a specialist.
5. Connect with the community. The Ehlers-Danlos Society (ehlers-danlos.com) has resources for both hEDS and HSD patients, including a healthcare provider directory.

The Future of the Classification

The 2017 criteria were explicitly described as interim, pending the identification of a genetic marker for hEDS. Research is ongoing, and it is likely that the classification will be revised in the coming years. When a genetic test for hEDS is eventually identified, the hEDS/HSD distinction may become less clinically relevant — or may be replaced entirely by a more nuanced molecular classification.

For now, the most important message is this: whether your chart says hEDS or HSD, your symptoms are real, your treatment needs are legitimate, and you deserve comprehensive care.