⚠ Medical Disclaimer
This article is for informational purposes only and does not constitute medical advice. GLP-1 medications require a prescription from a qualified healthcare professional. Always consult your GP or prescriber before starting, changing, or stopping any medication.
Rainbow Labs Weight Loss Review UK: Telehealth GLP-1 Service Compared
Rainbow Labs has built a different proposition to most UK GLP-1 services. Where the majority operate as simple prescribing platforms - questionnaire, approval, dispatch - Rainbow Labs combines telehealth consultations with at-home diagnostic testing and AI-assisted health monitoring.
The promise is a more personalised, data-driven weight management service. This review assesses whether the clinical process is sound, how the pricing compares, and where the service adds genuine value over simpler competitors.
Who Rainbow Labs Are
Rainbow Labs is a London-founded telehealth company operating across the UK. They are not a traditional online pharmacy - their model sits closer to a digital health clinic, built around diagnostic testing and data-driven clinical decisions.
Their weight management programme includes at-home blood test kits before and during treatment, AI-assisted interpretation of your health data, telehealth consultations with prescribers, GLP-1 prescriptions, and ongoing progress monitoring.
They are registered with the Care Quality Commission (CQC) and work with UK-registered prescribers. The diagnostic testing element is what distinguishes them most clearly from services like Click Pharmacy or Pharmacy2U.
The Weight Loss Programme: What You Actually Get
Initial Diagnostic Testing
Before any prescription is issued, Rainbow Labs send an at-home blood test kit. The standard panel covers HbA1c (blood glucose average), kidney function (eGFR, creatinine), liver function (ALT, AST), a full lipid profile, thyroid function (TSH), and a full blood count.
This is clinically sound practice. Most GLP-1 prescribers in the UK do not require baseline bloodwork - they rely on self-reported medical history. The problem with that approach is that conditions like elevated liver enzymes, impaired kidney function, or undetected type 2 diabetes can affect the safety and appropriateness of GLP-1 therapy. Rainbow Labs' insistence on baseline diagnostics before prescribing is a genuine clinical differentiator.
Key Takeaway
Baseline blood tests before GLP-1 therapy are not just box-ticking. Elevated liver enzymes, impaired kidney function, or undiagnosed type 2 diabetes can all affect which medication is appropriate and at what dose.
Telehealth Consultation
After results are available - typically within five to seven days of returning the sample - you attend a telehealth consultation with a prescriber. This is a live consultation, not an asynchronous form. The prescriber reviews your results alongside your completed health questionnaire.
This is a meaningful difference from form-only services. A prescriber who can see your HbA1c and kidney function in real time, and can ask follow-up questions based on what they see, is in a stronger position to make the right prescribing decision than one working from self-reported history alone.
AI-Assisted Monitoring
The AI element of Rainbow Labs' offering applies to ongoing health data interpretation. As you progress through treatment - and particularly as follow-up blood tests are taken - their system analyses trends, flags potential concerns, and surfaces them to the clinical team.
This is not AI prescribing or diagnosis. It is AI-assisted triage of health data, which enables the clinical team to prioritise which patients need proactive outreach. In practice, this means patients whose data shows concerning trends are more likely to receive a proactive call than they would at a service where follow-up is entirely patient-initiated.
Amy’s Take
I was sceptical about the "AI-driven results" framing before looking into this more carefully. A lot of health tech companies use AI as a marketing term for what is really just a dashboard. The Rainbow Labs implementation is more substantive than that - it is genuinely applied to flagging clinical patterns in longitudinal data. That said, the core clinical value is in the diagnostic testing before and during treatment. The AI element enhances that; it is not the foundation.
What Medications They Prescribe
Rainbow Labs prescribes Mounjaro (tirzepatide) across all standard dose steps from 2.5mg to 15mg, and Wegovy (semaglutide) from 0.25mg to 2.4mg.
They do not currently prescribe Ozempic off-label for weight management, which reflects the broader industry trend toward approved weight-loss formulations.
Prescribing decisions - including which medication is appropriate and at what starting dose - are made by the prescriber at consultation, informed by your blood test results and medical history.
Research
SURMOUNT-1, NEJM 2022
Tirzepatide 15mg produced 20.9% mean weight loss at 72 weeks. 57% of participants achieved 20%+ body weight reduction.
View study →Research
STEP 1, NEJM 2021
Semaglutide 2.4mg produced 14.9% mean weight loss at 68 weeks versus 2.4% for placebo. Nausea affected 44% of participants versus 16% on placebo.
View study →Eligibility
Standard criteria apply: BMI 30 or above, or BMI 27 or above with at least one weight-related comorbidity (type 2 diabetes, hypertension, cardiovascular disease, dyslipidaemia, obstructive sleep apnoea). No personal or family history of medullary thyroid carcinoma or MEN2 syndrome. Not pregnant or breastfeeding. No active or recent pancreatitis.
The blood test results can affect eligibility in ways that a self-reported questionnaire would not catch. Impaired kidney function, for example, may require dose modification or a specialist review before prescribing can proceed.
Pricing
Rainbow Labs' pricing reflects their more comprehensive model. The initial programme cost includes the at-home diagnostic testing and the telehealth consultation, followed by monthly prescription costs at the appropriate dose.
Initial diagnostic package: Typically £69 to £99 for the at-home blood test kit and AI analysis. This is a one-time upfront cost before prescribing begins.
Ongoing medication costs: Broadly in line with market rates for Wegovy and Mounjaro. Expect approximately £149 to £269 per month depending on medication and dose. Verify current pricing directly, as these change.
Total first-month cost: The diagnostic package plus first month's medication makes Rainbow Labs more expensive in month one than form-only services. The diagnostic component is clinically valuable and would cost £60 to £120 separately at Medichecks or Blue Horizon.
Follow-up testing: Rainbow Labs recommends repeat blood tests at three and six months. These are included in subscription packages and at additional cost otherwise.
20.9%
Mean weight loss with tirzepatide
SURMOUNT-1 trial at 72 weeks - the same drug prescribed via Rainbow Labs and all other UK services
The Diagnostic Model: The Case For and Against
The case for starting with blood tests: Most UK GLP-1 services do not require upfront blood tests. This means patients with undiagnosed thyroid problems, early kidney disease, or significantly elevated HbA1c may start GLP-1 therapy without the prescriber knowing about conditions that affect the appropriateness or management of treatment. Blood tests at the start are better clinical practice. Rainbow Labs is one of the few services that makes this standard rather than optional.
For GLP-1 monitoring best practices see our GLP-1 monitoring and bloodwork guide, which covers what should be tested and when.
The case against the extra step: For patients who are overweight without significant comorbidities, the upfront diagnostic requirement adds cost and a five to seven day delay. Click Pharmacy and Pharmacy2U can have medication to you in three to five days from application. Rainbow Labs adds a blood test phase to that timeline.
The additional cost - £69 to £99 for the diagnostic package - is real money that could go toward a month's medication.
Support and Follow-Up
Rainbow Labs includes ongoing access to their health platform, where you can view your results history, track changes over time, and message the clinical team.
Their follow-up model is stronger than a basic prescription service. The expectation is that you retest at intervals, and the platform is set up to facilitate that. The AI layer surfaces concerning trends to the clinical team, which means patients are more likely to receive proactive outreach than they would at a service where follow-up is entirely patient-initiated.
For comparison with other providers, see our best GLP-1 prescribers UK guide.
Rainbow Labs vs Standard Online Prescription Services
Who Rainbow Labs Works Well For
Good fit:
- Patients who want blood tests built into the service from the start rather than organised separately
- Those with risk factors (family history of diabetes, elevated blood pressure, possible thyroid issues) who want a diagnostic foundation before prescribing
- Patients who find raw lab results difficult to interpret and want a plain-English summary
- Those willing to pay a modest upfront premium for a more comprehensive clinical entry into treatment
Less ideal:
- Patients who want the fastest and cheapest route to a prescription
- Those who have had comprehensive blood tests through their GP in the past three months and do not need a repeat
- Price-focused patients for whom the £69 to £99 diagnostic step is a significant barrier
Rainbow Labs Weight Management Programme
Telehealth GLP-1 prescriptions with at-home diagnostic blood testing and AI-assisted health monitoring. UK-wide service with live prescriber consultations.
View on Rainbow Labs →Comparing Rainbow Labs to Click Pharmacy
If you are primarily motivated by cost and want the simplest route to a GLP-1 prescription, Click Pharmacy remains the most competitive option in the UK market. Their consultation process is thorough, prescribers are real, and medication arrives within a few days.
Rainbow Labs is the better choice if you want a more medically comprehensive entry into treatment, particularly if you have not had blood tests recently or if your medical history is complex enough to benefit from a live consultation with a prescriber who can see your results. Read our Click Pharmacy review for a direct comparison.
Frequently Asked Questions
How does the at-home blood test work? You receive a kit containing a lancet, collection tube, and prepaid envelope. You prick your finger, collect a small blood sample, and post it. Results arrive in your Rainbow Labs account within 3–5 business days.
Do I need the Rainbow Labs diagnostic package to get a prescription? Yes - the diagnostic is integrated into their weight management pathway. If you want to skip blood tests, a service like Pharmacy2U or Click Pharmacy allows you to apply directly.
Is Rainbow Labs AI-driven analysis safe? The AI analysis is a presentation layer and decision-support tool, not a diagnostic system. All prescribing decisions are made by registered clinicians who review your results and questionnaire. The AI does not prescribe.
What if my blood tests flag something concerning? The clinician reviewing your results will discuss the finding with you. Depending on severity, they may recommend you see your GP before proceeding, prescribe with additional monitoring requirements, or decline to prescribe until the concern is investigated.
Is Rainbow Labs regulated? Yes. They are CQC-registered and operate under standard UK telehealth regulation. Their prescribers hold appropriate UK prescribing qualifications.