Side-by-side · Research reference

SermorelinvsTeriparatide

Side-by-side comparison across mechanism, dosage, evidence, side effects, administration, and stack synergies. Citations on every claim where available.

APhase 3HUMAN-REVIEWED14/43 cited

BFDA-ApprovedHUMAN-REVIEWED10/62 cited

Sermorelin

GHRH 1-29 fragment · Short-acting

100–500 mcgPer doseMolteno 2013

Phase 3Evidence levelWalker 1994 Molteno 2013

~12 minHalf-lifeMolteno 2013

SQ · Pre-sleep · 1×/day

Teriparatide

PTH (1-34) Fragment · FDA-Approved

20 mcgDaily dose

12-18 moAnabolic windowFerrari 2026

SQRoute

SQ · Thigh/Abdomen · Once Daily

01Mechanism of Action

Parameter

Sermorelin

Teriparatide

Primary target

Pituitary GHRH receptorWalker 1994

Parathyroid hormone 1 receptor (PTH1R) on osteoblastsXue 2026

Pathway

GHRH-R → Gαs → cAMP → PKA → GH vesicle exocytosisWalker 1994

PTH1R activation → cAMP/PKA signaling → osteoblast differentiation and activity

Downstream effect

Pulsatile GH release; subsequent IGF-1 elevationMolteno 2013

Stimulates osteoblast formation and bone matrix deposition; increases bone mineral density at trabecular and cortical sites

Feedback intact?

Yes — short pulse preserves feedback

Yes — intermittent dosing preserves anabolic effect; continuous exposure causes catabolic bone resorption

Origin

Unmodified active 29-AA fragment of human GHRH (1-44)Walker 1994

Recombinant 34-amino-acid N-terminal fragment of 84-amino-acid human PTH

Antibody development

—

02Dosage Protocols

Parameter

Sermorelin

Teriparatide

Standard dose

100–500 mcg per injectionMolteno 2013

—

Frequency

Once daily, pre-sleep

Once daily

Intermittent administration preserves anabolic effect.

Lower / starter dose

100 mcg per dose

—

Evidence basis

Phase 3 (Geref pediatric); clinical practiceWalker 1994 Molteno 2013

RCT / FDA-approved

Duration

8–12 weeks per cycle

—

Reconstitution

Bacteriostatic water

—

Timing

Pre-sleep, fasted preferred

Morning or evening (flexible)

Half-life

~12 min (plasma)Molteno 2013

Shorter than tesamorelin (~26 min) — simpler GHRH analogue.

—

Standard dose (osteoporosis)

—

20 mcg / day

FDA-approved regimen for severe osteoporosis.

Maximum duration

—

24 months lifetime

Anabolic effect wanes after 12-18 months; FDA recommends max 2-year cumulative exposure.

Hypoparathyroidism dose

—

20 mcg / day

Used off-label for chronic hypoparathyroidism.

Pelvic fragility fractures

—

20 mcg / day × 8-12 weeks

Accelerates fracture healing; reduces time to union.Crooks 2026

Route

—

Subcutaneous (thigh or abdomen)

Storage

—

Refrigerate 2-8 °C; pen device stable at room temp for 28 days after first use

Pharmacogenetics

—

ALDH2 polymorphisms may influence BMD responseObara 2026

ALDH2*2 variant carriers show altered PTH receptor expression.Obara 2026

03Metabolic / Fat Loss Evidence

Parameter

Sermorelin

Teriparatide

Fat loss application

—

None — teriparatide is a bone anabolic agent without direct lipolytic activity

04Side Effects & Safety

Parameter

Sermorelin

Teriparatide

Injection site reaction

Mild erythema, transient pain

Erythema, bruising, pain (uncommon)

Flushing / headache

Common transient effect

—

IGF-1 elevation

Modest at standard doses

—

Cancer risk

Contraindicated in active malignancy (GH/IGF-1 axis)

—

Pregnancy / OB

Avoid

—

Glucose handling

Generally neutral

—

Hypercalcemia

—

Transient serum calcium elevation 4-6 hours post-injection

Monitor serum calcium; usually asymptomatic.

Orthostatic hypotension

—

Dizziness, lightheadedness within hours of injection

Nausea

—

Common, usually mild and transient

Leg cramps / Arthralgia

—

Musculoskeletal pain reported in clinical trials

Hypercalciuria

—

Increased urinary calcium excretion; monitor for nephrolithiasis risk

Osteosarcoma (black box warning)

—

Rat studies showed dose-dependent osteosarcoma; not observed in humans to date; contraindicated in Paget's disease, skeletal malignancy, prior radiation

Absolute Contraindications

Sermorelin

·Active malignancy
·Pregnancy / breastfeeding
·Disrupted hypothalamic-pituitary axis

Teriparatide

·Paget's disease of bone (increased baseline osteosarcoma risk)
·Unexplained elevated alkaline phosphatase
·Prior skeletal radiation therapy
·Skeletal malignancies or bone metastases
·Hypercalcemic disorders (primary hyperparathyroidism)
·Pregnancy / lactation

Relative Contraindications

Sermorelin

·Untreated diabetes

Teriparatide

·Active or recent nephrolithiasis
·Severe renal impairment (CKD G4-G5)
·Hypercalciuria without adequate monitoring

05Administration Protocol

Parameter

Sermorelin

Teriparatide

1. Reconstitution

Add 2 mL bacteriostatic water to 5 mg vial → 2.5 mg/mL = 250 mcg per 0.1 mL.

Teriparatide is supplied in pre-filled pen injectors (Forteo pen). Store refrigerated at 2-8 °C until first use. After first injection, pen may be kept at room temperature for up to 28 days. Do not freeze.

2. Injection site

SQ — abdomen or thigh. Rotate sites.

Subcutaneous injection into thigh or lower abdomen. Rotate sites daily to avoid lipodystrophy. Avoid areas with scars, bruises, or active skin conditions.

3. Timing

Pre-sleep, fasted.

Once daily, at approximately the same time each day. Morning or evening administration is acceptable. Take while sitting or lying down to minimize orthostatic hypotension risk.

4. Storage

Lyophilised: room temp, light-protected. Reconstituted: refrigerate ≤30 days.

Clean injection site with alcohol swab. Pinch skin, insert needle at 90° angle, and inject full dose (20 mcg). Hold for 5 seconds before withdrawing needle. Do not rub injection site.

5. Needle

29–31G, 4–8 mm insulin syringe.

Baseline and periodic monitoring of serum calcium, urinary calcium, serum PTH (if hypoparathyroidism), and bone mineral density (DXA scan). Monitor for hypercalcemia 4-6 hours post-dose if symptomatic.

6. Calcium and vitamin D supplementation

—

Ensure adequate calcium (1000-1200 mg/day) and vitamin D (800-1000 IU/day) intake unless contraindicated by hypercalcemia or hypercalciuria.

06Stack Synergy

Sermorelin

+ Ipamorelin

Strong

View Ipamorelin →

Sermorelin (GHRH analogue) and ipamorelin (selective GHRP) form the prototypical GHRH+GHRP dual-axis stack at the lowest cost. Both peak within 30 min and produce a sharp physiological GH pulse without cortisol/prolactin elevation.

Sermorelin: 200–300 mcg SQ · pre-sleep
Ipamorelin: 200–300 mcg SQ · same injection
Primary benefit: Pulsatile GH stimulation, recovery, body composition

Raun 1998 Walker 1994

Teriparatide

— no documented stacks