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GLP-1 Practical Guide

Disclaimer: This information is for educational purposes only and is not medical advice. GLP-1 medications require a prescription and medical supervision. Always consult your physician before starting, adjusting, or stopping any medication.

This guide covers the practical aspects of using GLP-1 peptide medications—from initial preparation through long-term maintenance. For background on how these medications work, their health benefits, and clinical trial evidence, see the companion GLP-1 Info Sheet. For dosing calculations, use the Peptide Calculator.

What You're Starting With

You've received a vial containing lyophilized (freeze-dried) peptide—a white powder or puck at the bottom of a small glass vial. This freeze-dried form is intentional: it's stable for years when stored properly, far longer than liquid form.

Before you can use it, you'll reconstitute the powder by adding bacteriostatic water, creating an injectable solution. Once mixed, you'll store this vial in your refrigerator and draw your weekly doses from it over the coming weeks.

This guide walks through the entire process: gathering supplies, reconstituting your peptide, injecting, and managing your dose over time.

Required Supplies

Before you begin, gather the following:

For Reconstitution

Bacteriostatic water — Use only pharmaceutical-grade bacteriostatic water, specifically Hospira brand. Avoid bacteriostatic water sold on Amazon, as quality and sterility are inconsistent.

3 mL syringes — For transferring bacteriostatic water to the peptide vial. Luer-lock syringes provide a secure needle connection.

Drawing needles — 25 gauge, 1.5" needles attach to the 3 mL syringes for reconstitution.

For Injection

Insulin syringes — Choose based on the volume you'll be injecting:

0.5 mL syringes for most doses (recommended)
1 mL syringes for larger doses

These come with needles attached (30-31 gauge, 5/16" length)—ideal for subcutaneous injection.

General Supplies

Alcohol swabs — For sterilizing vial tops and injection sites.

Sharps container — Any hard-sided container with a lid (e.g., empty laundry detergent bottle) for safe needle disposal.

Reconstitution

Reconstitution converts the lyophilized (freeze-dried) peptide powder into an injectable liquid.

How Much Bacteriostatic Water to Add

The amount of water you add determines your concentration, which affects how much volume you'll inject for each dose. Use the Peptide Calculator to determine the optimal amount based on your vial size, target dose, and preferred injection volume.

General principle: Higher concentrations mean smaller injection volumes but require more precise measurement. Lower concentrations are easier to measure but require injecting more liquid.

Understanding Concentrations

When you reconstitute a peptide, the amount of water you add determines your concentration. More water = more dilute = larger injection volumes. Less water = more concentrated = smaller injection volumes.

The math is simple: Concentration = total peptide ÷ water added.

Example: A hypothetical 30 mg vial

If you add 3 mL of water to a 30 mg vial:

Concentration = 30 mg ÷ 3 mL = 10 mg/mL

If you add 1.5 mL of water to the same 30 mg vial:

Concentration = 30 mg ÷ 1.5 mL = 20 mg/mL

Your vial size will vary—use the same formula with your actual vial size and water amount to calculate your concentration.

Converting mg to units: Insulin syringes measure in "units" where 100 units = 1 mL. Once you know your concentration, you can calculate how many units to draw for any dose:

If your concentration is...	To inject 1 mg, draw...	To inject 2 mg, draw...
5 mg/mL	20 units	40 units
10 mg/mL	10 units	20 units
20 mg/mL	5 units	10 units

Or use the Peptide Calculator to do the math for you.

Procedure

Prepare your workspace — Clean, well-lit area with all supplies ready.
Remove caps — Take off the colored plastic caps from both the peptide vial and bacteriostatic water vial. Leave the metal crimp cap with rubber stopper in place.
Prepare the syringe — Draw air into your syringe equal to the amount of bacteriostatic water you'll use.
Swab and draw — Alcohol swab the bacteriostatic water vial top, insert needle, push in air, draw out the desired amount of water.
Add to peptide vial — Alcohol swab the peptide vial top, insert needle, slowly inject the bacteriostatic water. Aim the stream at the vial wall, not directly at the powder.
Mix gently — Let sit or gently swirl until powder is fully dissolved. Do NOT shake vigorously. The solution should be clear with no visible particles.
Dispose of needle safely — Place used needles in your sharps container.
Store reconstituted vial — Refrigerate immediately. Label with date and concentration.

Injection Technique

GLP-1 medications are administered as subcutaneous injections (into fat tissue, not muscle).

Injection sites — Common sites, in order of typical preference:

Abdomen (most convenient; avoid 2 inches around the navel)
Thigh (front or outer thigh)
Upper arm (back of upper arm; may need assistance)

Rotate sites between injections to minimize irritation.

Procedure:

Draw your dose — Attach a fresh needle to your syringe, swab the vial top, draw air equal to your dose, insert needle, push in air, draw out your dose. Remove any air bubbles by tapping the syringe and pushing them out.
Prepare injection site — Swab the area thoroughly with alcohol and let dry.
Pinch the skin — For very lean individuals, pinching a fold of skin ensures subcutaneous delivery.
Insert needle — At a 90-degree angle for most people, or 45 degrees if very lean. Insert fully.
Inject slowly — Push the plunger steadily. There's no rush.
Wait briefly — Count to 5 before withdrawing to ensure full delivery.
Withdraw and dispose — Remove needle, dispose in sharps container. Apply light pressure if there's any bleeding.

Dosing Schedules

Standard FDA Schedules

The schedules below are the official FDA-approved titration protocols. However, many practitioners and users prefer starting at lower doses and increasing more gradually than these schedules suggest—this dramatically reduces side effects without meaningfully slowing results. See Low and Slow Titration below for an alternative approach.

Semaglutide:

Week	Weekly Dose
1-4	0.25 mg
5-8	0.50 mg
9-12	1.0 mg
13-16	1.7 mg
17+	2.4 mg

Tirzepatide:

Week	Weekly Dose
1-4	2.5 mg
5-8	5.0 mg
9-12	7.5 mg
13-16	10.0 mg
17-20	12.5 mg
21+	15.0 mg

Retatrutide (Anticipated/Investigational):

Week	Weekly Dose
1-4	2.0 mg
5-8	4.0 mg
9-12	8.0 mg
13+	12.0 mg

Note: Lighter individuals or women may prefer starting at 1.0 mg for retatrutide.

Low and Slow Titration

Slower titration dramatically reduces side effects. Clinical trials confirm that gradual dose increases result in less than half the days of nausea compared to standard schedules—without meaningfully slowing total weight loss.

Low and Slow Schedule (Tirzepatide/Retatrutide)

For those sensitive to side effects or wanting to minimize GI disturbance, start at 0.5 mg/week and increase by 0.25-0.5 mg each week until reaching your effective dose. Use the Peptide Calculator to determine injection volumes for your concentration.

Week	mg/week	Units @ 5mg/mL	Units @ 10mg/mL	Units @ 20mg/mL
1	0.50	10	5	2.5
2	0.75	15	7.5	3.75
3	1.00	20	10	5
4	1.25	25	12.5	6.25
5	1.50	30	15	7.5
6	1.75	35	17.5	8.75
7	2.00	40	20	10
8	2.50	50	25	12.5
9	3.00	60	30	15
10	3.50	70	35	17.5
11	4.00	80	40	20
12	4.50	90	45	22.5
13	5.00	100	50	25
14	5.50	110	55	27.5
15	6.00	120	60	30
16	6.50	130	65	32.5
17	7.00	140	70	35
18	7.50	150	75	37.5
19	8.00	160	80	40

Key Principles

Start small — 0.5 mg is a reasonable starting point for most people.

Increase gradually — 0.25-0.5 mg per week.

Listen to your body — If a dose feels uncomfortable, stay there or reduce slightly before continuing.

No rush — Slower titration does not meaningfully reduce total weight loss over time.

Find your effective dose — Not everyone needs maximum doses; many plateau at moderate doses.

Split Dosing (Advanced)

Some people report better tolerance with split dosing—instead of 4 mg once weekly, inject 2 mg twice weekly. This smooths out circulating levels and may reduce peak-related side effects.

While on Therapy

Because these medications reduce food volume, most people unintentionally reduce intake of vitamins, minerals, and fiber. The following modifications help maintain nutritional status and preserve lean mass.

Micronutrients

Take a high-quality multivitamin daily (e.g., Thorne Basic Nutrients 2/Day). A significant proportion of long-term users develop at least one nutrient deficiency over time.

Fiber

Supplement with psyllium husk: start at 3-5 g/day, gradually increase to ~10 g/day. Take with adequate fluid and 2+ hours apart from other medications (fiber can reduce absorption).

Protein and Lean Mass

The proportion of lean vs. fat lost is similar to dieting alone when matched for total weight loss—these medications are not uniquely catabolic. However, 15-40% of weight lost may be lean mass. To minimize this:

Strength training: 2-3 sessions/week focusing on major movement patterns
Protein intake: 0.7-1.0 g per lb body weight daily (prioritize this macro)

Hydration and Movement

Fluids: Aim for 2-3 L/day (thirst cues may be blunted on these medications)
Daily steps: Maintain 7,000-10,000 steps as a baseline activity level

Maintenance Dosing

After achieving target weight, several approaches can maintain results. Real-world data shows 56% of people maintain weight loss 1-2 years after stopping entirely, and those who continue at reduced doses do even better.

Strategies

Continue weekly at lower dose — Reduce from therapeutic dose (e.g., 4 mg) to maintenance dose (e.g., 1 mg). Many people maintain full weight loss indefinitely this way.

Every-other-week dosing — Switch from weekly to bi-weekly injections. Maintains approximately 75% of weight loss effect while significantly reducing cost and medication burden.

Gradual tapering — Reduce dose over several weeks before discontinuing. May result in better maintenance than abrupt cessation.

Medication transition — Some transition to phentermine after reaching target weight. Those who lost >15% body weight report this transition feels considerably easier.

High-protein maintenance diet — Maintaining protein intake at 0.7-1.0 g/lb supports lean mass and satiety after discontinuation.

What the Data Shows

56% maintain weight loss 1-2 years after stopping (EPIC Research, 38,000 patients)
Only 18% regain everything
Average regain without maintenance strategy is ~1 pound/month
Retatrutide users appear to maintain better than semaglutide users
The SURMOUNT-MAINTAIN trial (expected 2026) will provide definitive data on optimal approaches

Managing Side Effects

The most common side effects are gastrointestinal: nausea, constipation, or diarrhea. These typically occur during dose escalation and resolve within 1-2 weeks. Slower titration dramatically reduces these effects.

Agent Differences

Tirzepatide and retatrutide have roughly half the GI side effect rates of semaglutide due to weaker GLP-1 receptor activation buffered by GIP signaling. Switching agents often resolves issues entirely if one medication isn't tolerated.

Nausea

Eat smaller, more frequent meals rather than large portions
Avoid high-fat foods which slow gastric emptying further
Stay upright 30 minutes after eating
If persistent after dose increase, drop back to previous tolerated dose and stay there 2+ weeks before trying again
Consider smaller increments (0.25 mg instead of 0.5 mg)

Constipation

Proactive psyllium supplementation (see While on Therapy section)
Adequate hydration — at least 2-3 L/day
Regular physical activity
Magnesium citrate if needed

Injection Site Reactions

Redness, itching, or swelling are common and usually mild.

Rotate injection sites (abdomen, thigh, upper arm)
Ice the area before injection if sensitive
Usually diminishes with continued use

Missed Doses

If less than 5 days until next scheduled dose, skip the missed dose
If more than 5 days, take the missed dose, then resume normal schedule
Never double up doses

Troubleshooting (Reconstitution and Storage)

Peptide won't dissolve — Be patient; it can take several minutes. Gently swirl; don't shake. If particles remain after 10 minutes, the peptide may be degraded.

Cloudy solution — Solution should be clear and colorless. Cloudiness may indicate contamination or degradation. When in doubt, discard and use a fresh vial.

Storage and Shelf Stability

GLP-1 peptides are remarkably stable when stored properly. Claims from some sources about short shelf lives are often exaggerated.

Before Reconstitution (Lyophilized/Powder Form)

Frozen (-20°C or below) — Shelf life of 5+ years. Novo Nordisk data shows semaglutide stable through 60 months when frozen. This is the optimal long-term storage method.

Refrigerated (2-8°C / 36-46°F) — Stable for 2+ years. FDA and EMA approval documents confirm 24-36 month stability for tirzepatide and semaglutide.

Room temperature (20-25°C / 68-77°F) — Stable for several months. Not ideal for long-term storage, but acceptable for shorter periods.

After Reconstitution

Refrigerated (2-8°C) — Stable for several months to years. Novo Nordisk showed 6 months stability at 25°C for reconstituted semaglutide. Do NOT freeze reconstituted peptides—this damages the molecule.

Room temperature — Tirzepatide stable up to 21 days below 30°C (86°F). Semaglutide stable up to 28 days below 30°C. Acceptable for travel, but refrigeration is preferred.

Practical Recommendations

For stockpiling — Keep vials frozen and non-reconstituted.

For active use — Refrigerate reconstituted vials.

Bacteriostatic water — Good for 28 days officially, but appears stable through 9+ months in practice. Refrigerate after opening and always swab the top prior to inserting a needle.