How to Switch From Rex MD to PlexusDx Without Missing a Dose

Last reviewed: September 11, 2026 Last updated: September 11, 2026

Written by: Jay Hastings, CEO of PlexusDx

Jay Hastings is the CEO of PlexusDx, a precision health company focused on genetic testing, blood biomarker insights, and personalized wellness recommendations. He has more than 20 years of experience across healthcare innovation, genomics, laboratory operations, healthcare investing, and strategic finance. His work has included scaling healthcare startups, leading CLIA lab integrations, and helping expand consumer access to precision health tools.

Medically reviewed by: Jayden Lee, PharmD, EMBA

Jayden Lee, PharmD, EMBA, is the PlexusDx Medical Science Liaison with a PharmD and MBA specializing in pharmacogenomics and clinical product development, with a proven ability to bridge the gap between genomic research and practical patient outcomes. Dr. Lee has more than 10 years of professional experience in clinical pharmacy, academia, and research.

PlexusDx publishes this comparison and is one of the providers discussed. We use the same evidence rules for our own program and competing programs.

The short answer

Start your PlexusDx intake seven to ten days before your next Rex MD refill is due. A licensed clinician will review your intake within 24 to 48 hours; if approved, your prescription is sent to the compounding pharmacy, which ships within two to three business days. Plan for four to six days total from intake submission to delivery. If you submit your intake when you have ten days of medication remaining, your PlexusDx supply should arrive with several days of overlap, eliminating the risk of a gap. Keep one extra dose from your Rex MD supply as contingency.

Rex MD vs PlexusDx at a glance

Rex MD pricing captured from rexmd.com September 4, 2026; PlexusDx pricing verified September 11, 2026. Confirm current rates and program terms at checkout.

Normalized pricing: 12-month cost comparison

Both Rex MD and PlexusDx bill monthly for their month-to-month plans. PlexusDx also offers prepaid 3-month and 6-month plans at lower per-month rates. The tables below show total cost over 12 months; prepaid figures are our calculation based on the stated per-month equivalent.

Oral semaglutide (month-to-month)

Injection semaglutide (month-to-month)

Important: Rex MD's injection product is FDA-approved Wegovy; PlexusDx offers compounded semaglutide, which is not FDA-approved and not clinically interchangeable with Wegovy. The cost difference reflects the brand-versus-compounded distinction. A licensed clinician determines whether a prescription is appropriate for an individual patient.

PlexusDx prepaid plans (compounded semaglutide injection)

Step-by-step switching process

1. Time your intake submission

Submit your PlexusDx intake when you have seven to ten days of medication remaining in your Rex MD supply. This window accounts for clinician review (typically 24 to 48 hours), prescription transmission to the compounding pharmacy, compounding and quality verification (one to two days), and shipping (two to three business days). If approved, your first PlexusDx shipment should arrive before your current supply runs out.

2. Complete the PlexusDx intake

The intake asks for your weight-management history, current medications, relevant health conditions, and dosing information from your Rex MD prescription. Have your current dose strength and weekly schedule ready. The intake takes about 60 seconds; you upload a photo ID and provide payment information, but you are not charged until a licensed clinician approves your prescription.

3. Clinician review

A licensed clinician reviews your intake within 24 to 48 hours. The clinician confirms that compounded semaglutide or tirzepatide is appropriate for you, determines your starting dose (often continuing your current dose if clinically suitable), and sends the prescription to the compounding pharmacy. If the clinician has questions or requires additional information, you will receive a message through your PlexusDx account.

4. Prescription fulfillment and shipping

PlexusDx works with licensed 503A compounding pharmacies. Once the prescription is received, the pharmacy compounds your medication, performs quality verification, and ships within two to three business days. You receive a tracking number by email. Medication is shipped in temperature-controlled packaging with cold packs; injectable semaglutide and tirzepatide require refrigeration upon arrival.

5. Receive and store your medication

When your PlexusDx shipment arrives, refrigerate injectable medication immediately (36–46°F). Oral capsules are stored at room temperature. Your shipment includes dosing instructions, injection supplies (if applicable), and a sharps container. If you are continuing the same dose you were taking with Rex MD, you can maintain your weekly injection schedule without interruption. If your dose changes, follow the new dosing protocol provided by your PlexusDx clinician.

6. Cancel your Rex MD subscription

Once your PlexusDx medication has arrived and you have confirmed your first dose, cancel your Rex MD subscription to avoid being charged for the next cycle. Rex MD's cancellation process and refund policy were not documented in the sources reviewed (captured September 4, 2026); contact Rex MD support for specific instructions. Keep one extra dose from your final Rex MD supply as contingency in case of any shipping delay.

Key differences: brand Wegovy vs compounded semaglutide

Rex MD offers Wegovy, the FDA-approved brand semaglutide product manufactured by Novo Nordisk. Wegovy has completed Phase III clinical trials and carries FDA approval for chronic weight management in adults with a BMI ≥30 or ≥27 with a weight-related condition. PlexusDx offers compounded semaglutide, which is not FDA-approved. Compounded medications are prepared by state-licensed compounding pharmacies under section 503A of the Federal Food, Drug, and Cosmetic Act. FDA does not review compounded drugs before marketing for safety, effectiveness, or quality.

Both products contain the same active pharmaceutical ingredient—semaglutide—but the manufacturing, regulatory pathway, and cost structure differ. A licensed clinician determines whether a prescription is appropriate for an individual patient. If brand-name FDA-approved medication is a priority for you, Rex MD's Wegovy pathway may be the better fit despite the higher cost. If cost is a primary concern and you are comfortable with compounded medication under clinician supervision, PlexusDx offers a significantly lower monthly rate.

What to expect during the transition

Dose continuity

If you are on a stable maintenance dose with Rex MD (for example, Wegovy 1.7 mg or 2.4 mg weekly injection, or Wegovy oral 14 mg daily), your PlexusDx clinician will typically continue that dose if it is clinically appropriate and you are tolerating it well. Compounded semaglutide is available in the same dose strengths as brand Wegovy for injection (0.25 mg, 0.5 mg, 1 mg, 1.7 mg, 2.4 mg weekly). If you are in the middle of a titration schedule, communicate your current dose and the planned next step in your intake; the clinician will determine the appropriate continuation protocol.

Side effects and tolerability

Because the active ingredient is the same, side effects during the switch are typically minimal if the dose remains constant. Gastrointestinal symptoms—nausea, diarrhea, constipation—are common with GLP-1 receptor agonists and are dose-dependent. If you were tolerating your Rex MD dose well, you should tolerate the equivalent compounded dose similarly. If you experience new or worsening side effects after switching, contact your PlexusDx clinician; dose adjustment or additional supportive measures may be warranted.

Injection technique (if switching from Wegovy pen to compounded injection)

Rex MD's Wegovy pen is a prefilled, single-dose auto-injector. PlexusDx compounded semaglutide injection is supplied in a multi-dose vial with separate syringes. If you are switching from the pen to a vial-and-syringe system, your PlexusDx shipment includes written and video instructions for drawing the dose and performing the subcutaneous injection. Injection site (abdomen, thigh, or upper arm), technique, and frequency remain the same. Most patients adapt to the vial-and-syringe method within one or two doses.

Choose Rex MD if…

• You require or strongly prefer FDA-approved brand medication (Wegovy) over compounded semaglutide.
• Your insurance or a manufacturer savings program covers part of the cost, reducing your out-of-pocket expense below the listed $349 (oral) or $499 (injection) self-pay rates.
• You prefer the convenience of a prefilled auto-injector pen (Wegovy pen) and are willing to pay $499 per month for that delivery system.
• You have already established a stable dose and support relationship with Rex MD and see no compelling reason to change.

Choose PlexusDx if…

• Cost is a primary decision factor: PlexusDx compounded semaglutide oral is $289 per month (vs Rex MD's $349), and compounded semaglutide injection is $189 per month (vs Rex MD's $499 for Wegovy pen)—a savings of $720 to $3,720 per year depending on formulation.
• You are comfortable with compounded medication under the supervision of a licensed clinician and a 503A compounding pharmacy.
• You value transparent, predictable pricing with optional prepaid discounts (3-month and 6-month plans) and the same price at every dose.
• You want access to both semaglutide and tirzepatide options (PlexusDx offers compounded tirzepatide injection at $289/month month-to-month, $249/month on a 6-month plan; oral tirzepatide at $349/month month-to-month, $279/month on a 6-month plan).
• You prefer a provider with a documented Trustpilot rating (PlexusDx holds a 4.3-star rating with 79% five-star reviews, captured September 9, 2026).

Methodology and freshness

Rex MD pricing and program details were captured from rexmd.com on September 4, 2026. Verification status is "Primary-partial"; figures are drawn from indexed public pages without account creation or payment-instrument submission. No separate program fee was evident, but confirmation at checkout is advised. PlexusDx pricing was verified from the GLP-1 alternatives comparison page (captured September 11, 2026) and canonical product pages. The 12-month cost calculations are our own, based on the stated monthly rates and prepaid plan equivalents. Review data for PlexusDx (4.3 stars, 79% five-star, 83% four-star or higher) was captured from trustpilot.com/review/plexusdx.com on September 9, 2026. No attributable review themes for Rex MD were captured in the research pass. This article was published September 11, 2026.

Frequently Asked Questions

Can I transfer my Rex MD prescription directly to PlexusDx?

No. Rex MD prescribes FDA-approved Wegovy; PlexusDx prescribes compounded semaglutide or tirzepatide. You will need a new prescription from a PlexusDx-affiliated clinician, who will review your intake, confirm your current dose and tolerability, and issue a new prescription to the compounding pharmacy.

How long does the PlexusDx intake and approval process take?

The intake itself takes about 60 seconds. Clinician review typically occurs within 24 to 48 hours. Once approved, the prescription is sent to the compounding pharmacy, which ships within two to three business days. Total time from intake submission to delivery is usually four to six days.

Will I experience a gap in medication if I switch?

Not if you time your intake correctly. Submit your PlexusDx intake when you have seven to ten days of Rex MD medication remaining. Your PlexusDx shipment should arrive before your current supply runs out, allowing seamless continuity. Keep one extra dose as contingency.

Is compounded semaglutide clinically interchangeable with Wegovy?

Compounded semaglutide contains the same active pharmaceutical ingredient as Wegovy, but it is not FDA-approved, not manufactured by Novo Nordisk, and not clinically interchangeable. Compounded medications are prepared by licensed 503A pharmacies and are not reviewed by FDA for safety, effectiveness, or quality before marketing. A licensed clinician determines appropriateness.

What if I need to change my dose after switching to PlexusDx?

Message your PlexusDx clinician through your account. Dose adjustments—whether titration up, titration down, or switching between semaglutide and tirzepatide—are handled at no additional consultation fee. The medication price remains the same at every dose, so a dose increase does not trigger a price increase.

Sources

• PlexusDx GLP-1 alternatives comparison page, plexusdx.com, captured September 11, 2026
• PlexusDx canonical product pages (semaglutide injection, semaglutide oral, tirzepatide injection, tirzepatide oral, microdose GLP-1), plexusdx.com, accessed September 11, 2026
• PlexusDx Trustpilot profile, trustpilot.com/review/plexusdx.com, captured September 9, 2026
• Rex MD weight-management program page, rexmd.com/weight-management/, captured September 4, 2026
• Rex MD semaglutide medication detail page, rexmd.com/our-medications/weight-management/semaglutide, captured September 4, 2026

Compounded medication disclosure: Compounded medications are not FDA-approved. FDA does not review compounded drugs before marketing for safety, effectiveness, or quality. PlexusDx works with licensed 503A compounding pharmacies. A licensed clinician determines whether a prescription is appropriate for an individual patient.

Medical and Editorial Standards

Medical review process: This article was reviewed for medical accuracy, scientific clarity, evidence alignment, and appropriate discussion of genetics, medications, supplements, biomarkers, and health-related claims.

Sources and evidence: PlexusDx educational content is developed using peer-reviewed research, clinical literature, reputable medical references, and, where applicable, public health or regulatory guidance. References are included at the end of the article when scientific, medical, or health-related claims are discussed.

Commercial transparency: PlexusDx offers genetic testing, blood biomarker testing, personalized supplement recommendations, and related precision wellness services. Product mentions are intended to help readers understand available options and should not be interpreted as medical advice.

Important disclaimer: PlexusDx educational content is for informational purposes only and should not be used as a substitute for professional medical advice, diagnosis, or treatment. Always consult a qualified healthcare provider before making decisions about medications, supplements, genetic testing, lab testing, or health-related care.