Injection Techniques & Safety

Video tutorial available

For a visual walkthrough, watch the Planned Parenthood self-injection tutorial below. The text guide follows for reference.

IM vs Subcutaneous: Which Route?

Factor	Intramuscular (IM)	Subcutaneous (SC)
Needle length	1-1.5 inches (25-38 mm)	0.375-0.625 inches (10-16 mm)
Injection angle	90 degrees	45-90 degrees (pinch skin)
Typical volume	0.5-1 mL (up to 3 mL max per site)	0.2-0.5 mL (up to 1.5 mL max)
Absorption speed	Faster peak, slower drop-off	Slower, more even absorption
Pain level	Moderate	Low
Site options	Ventrogluteal, thigh, gluteal, deltoid	Abdomen, thigh, upper arm, lower back
Common for	T cypionate, T enanthate, EV, EC	EEn, some T protocols, low-volume injections

IM injections deposit medication deep into muscle tissue, which has richer blood supply and can handle larger volumes. SC injections deposit into the fatty layer beneath the skin and are generally less painful, with lower risk of hitting a blood vessel or nerve.

Many people on estrogen monotherapy (EEn, EC) find SC injections work well with smaller needles and less discomfort. Testosterone cypionate and enanthate are traditionally given IM but some people use them SC with good results, though absorption may be slower.

Equipment

Syringes

Size	Use
1 mL (insulin/ tuberculin)	Best for precise dosing of small volumes (0.1-1 mL). Markings every 0.01 mL allow accurate dosing.
3 mL	Common for larger doses or if 1 mL syringes are hard to find. Markings every 0.1 mL are less precise for small doses.

Luer lock syringes are preferred over luer slip because the needle screws on securely and will not pop off during injection.

Low dead space syringes reduce the amount of medication left in the hub after injection. This saves medication over time and is relevant when doses are small or medication is expensive.

Needles

Gauge	Color (ISO standard)	Typical Use
18G	Pink	Drawing thick oil from vial
20G	Yellow	Drawing medication
21G	Green	Drawing or injecting (IM)
22G	Black	Drawing or injecting (IM)
23G	Blue	Injecting IM (some discomfort)
25G	Orange	Injecting IM or SC (good balance)
27G	Grey	Injecting SC (lowest pain)
28-30G	Various	Insulin syringes (SC only)

Drawing needles: 18-20G is standard for oil-based medication. The oil is viscous and a larger gauge makes drawing faster and prevents air bubbles.

Injection needles: 25G is a common compromise between comfort and flow. 27G is thinner and hurts less but requires more force to push the plunger. Some oil-based medications (especially T cypionate) are thick and may be hard to inject through 27G or smaller.

Needle length: For IM, use 1 inch for deltoid or lean thigh, 1.25-1.5 inches for ventrogluteal or gluteal depending on body size. For SC, a 0.375-0.625 inch (10-16 mm) needle is standard.

Other Equipment

• Alcohol swabs: 70% isopropyl alcohol. Use one on the vial stopper and one on the injection site.
• Sharps container: FDA-approved sharps bin or a thick puncture-proof container (laundry detergent bottle) as temporary alternative.
• Bandages / plasters: Optional, for the injection site.
• Gloves: Not required for self-injection but useful if you have trouble with sterile technique.

For a full injection kit checklist and country-by-country supplier list, see the Needle & Syringe Sourcing guide.

Finding Injection Sites

Ventrogluteal (IM) - Best for self-injection

Place the palm of your hand on the greater trochanter (the bony bump on the outside of your hip). Point your index finger toward the front of your hip (anterior superior iliac spine) and your middle finger toward the iliac crest (top of your hip bone). The injection goes in the triangle of flesh between your index and middle fingers, on the side of your hip.

This site is the largest muscle accessible for IM injection, has fewer major nerves and blood vessels, and handles larger volumes well.

Vastus Lateralis (Thigh) (IM)

The injection goes into the outer middle third of your thigh, halfway between knee and hip, on the outer side of the thigh. Divide your thigh into thirds horizontally and aim for the middle third. Avoid the inner thigh (major blood vessels) and the front center (femoral nerve).

This is the easiest site for self-injection because you can see what you are doing, but it can be more painful than ventrogluteal.

Gluteal (Buttock) (IM)

Divide the buttock into four quadrants. Inject into the upper outer quadrant only. The lower inner quadrant contains the sciatic nerve and major blood vessels. This site is hard to reach for self-injection and is better done by another person.

Dorsogluteal site not recommended

Current CDC and WHO injection guidelines recommend against the dorsogluteal (upper outer buttock) injection site due to its proximity to the sciatic nerve and gluteal vessels. The ventrogluteal or vastus lateralis (thigh) sites are preferred for self-injection. Do not inject into the lower inner or center of the buttock.

Abdomen (SC)

Choose an area 1-2 inches away from the belly button. Pinch a fold of skin. Inject at a 45-90 degree angle into the pinched skin. Rotate around the abdomen, leaving space between sites. Avoid the waistband area where friction can cause irritation.

Upper Thigh and Arm (SC)

The outer upper arm and the front/outer thigh can also be used for SC injections. These sites work well but have less fatty tissue than the abdomen.

Step-by-Step Injection Guide

Preparation

1. Gather all equipment: syringe, drawing needle, injection needle, alcohol swabs, sharps container, bandage.
2. Wash hands thoroughly with soap and water for 20 seconds.
3. If the medication has been refrigerated, let it sit at room temperature for 10-15 minutes. Cold oil is thicker and hurts more.
4. Check the vial for visible particles, discoloration, or cracks. Do not use if anything looks wrong.
5. Clean the vial stopper with an alcohol swab. Let it dry (at least 10 seconds).

Homebrew Injectables: Syringe Filter Required

If using a homebrew injectable (not a pharmaceutical vial with a sealed rubber stopper from a licensed manufacturer), you must filter the drawn solution through a 0.22 μm (0.2 μm) sterile syringe filter before injecting.

Why: Homebrew preparations are not manufactured under pharmaceutical clean-room conditions. A 0.22 μm filter sterilises the solution of bacteria, fungal spores, and many particulates that could cause injection-site infections, abscesses, or systemic sepsis.

How:

1. Draw your dose with the drawing needle as normal.
2. Remove the drawing needle and attach a sterile 0.22 μm PES or PVDF syringe filter (available from lab supply stores, Amazon, etc.).
3. Slowly push the solution through the filter into a second sterile syringe OR attach your injection needle directly to the filter output port.
4. Replace the filter with your injection needle and proceed.
5. If you feel strong resistance while pushing, the filter may be saturated — use a fresh filter.

Note: 0.22 μm filters are not needed for sealed pharmaceutical vials (e.g., Depo-Estradiol, Delestrogen) which are already sterile. They are required for homebrew and any solution drawn from non-pharmaceutical vials.

Drawing the Medication

1. Attach the drawing needle to the syringe.
2. Pull back the plunger to draw air equal to your dose volume.
3. Insert the needle into the vial through the center of the stopper.
4. Inject the air into the vial. This prevents a vacuum from forming.
5. Turn the vial upside down. Hold it steady.
6. Pull back the plunger slowly to draw slightly more than your dose.
7. Tap the syringe to dislodge air bubbles, then push them back into the vial.
8. Adjust the plunger to exactly your dose.
9. Remove the needle from the vial.
10. Replace the drawing needle with the injection needle. Remove the cap carefully.

Tip for thick oil: If the oil is hard to draw, warm the vial under your armpit or in your hand for a few minutes. Do not microwave or heat directly. Running warm (not hot) tap water over the vial for 30-60 seconds can also help.

Choosing and Cleaning the Site

1. Select a site based on your rotation schedule (see below).
2. Clean the skin with a fresh alcohol swab. Start at the center and work outward in a spiral motion. Cover an area about 2-3 inches across.
3. Let the alcohol dry completely. This takes 15-30 seconds. Wet alcohol stings going in.

Injecting

For IM injections:

1. Stretch the skin flat at the injection site using your non-dominant hand (Z-track method).
2. Insert the needle at a 90-degree angle with a quick, steady motion.
3. Do not aspirate (pull back the plunger). Modern guidelines from the CDC, WHO, and AMA recommend against routine aspiration for IM and SC injections — it does not improve safety and increases injection pain. If blood appears in the needle hub during insertion (rare, indicating a vessel is under pressure), withdraw the needle immediately, apply pressure for 1–2 minutes, and use a fresh needle at a different site.
4. Inject slowly. Aim for about 10 seconds per 0.5 mL. Faster injection causes more pain and tissue damage.
5. Wait 5 seconds after finishing before withdrawing.
6. Withdraw the needle at the same angle it went in.
7. Apply dry cotton ball or gauze with light pressure. Do not rub or massage the site.

For SC injections:

1. Pinch a fold of skin between your thumb and forefinger.
2. Insert the needle at a 45-90 degree angle (depending on the amount of subcutaneous tissue).
3. Do not aspirate (same reasoning as IM).
4. Inject slowly, about 10 seconds per 0.5 mL.
5. Release the pinched skin.
6. Withdraw the needle at the same angle.
7. Apply light pressure. Do not rub.

Z-track technique (for IM): Pull the skin slightly to one side before inserting the needle. Once the needle is in, release the skin. This creates a zigzag track that seals the medication in the muscle and reduces leakage back into the subcutaneous tissue. It also reduces pain and irritation at the site.

Air-lock technique: Draw a small amount of air (0.1-0.2 mL) after the medication, then inject. The air bubble at the end clears the needle hub so you get the full dose and helps seal the injection track.

Disposal

1. Immediately place the used needle and syringe into a sharps container. Do not recap the needle.
2. Store the sharps container in a safe place away from children and pets.
3. When the container is three-quarters full, seal it and dispose of it at a designated collection site.

Injection Rotation Schedules

Rotating injection sites prevents scar tissue buildup (lipohypertrophy), reduces pain, and ensures consistent absorption.

IM Rotation

Injection Number	Site	Side
1	Ventrogluteal	Right
2	Ventrogluteal	Left
3	Vastus lateralis	Right
4	Vastus lateralis	Left
5	Ventrogluteal	Right
(repeat cycle)

Aim to leave at least 2-3 days between injections in the same general area and at least 1 week between injections in the exact same spot (if injecting weekly or more frequently).

SC Rotation

Week	Quadrant of Abdomen	Notes
1	Upper right	2 inches from belly button
2	Upper left
3	Lower left
4	Lower right
5	Repeat cycle	Or add upper arms/thighs

Leave at least 1 inch between SC injection sites. Mark previous sites mentally or in a log.

Injection Frequency by Ester

Ester	Typical Half-Life	Typical Frequency	Common Dose	Monotherapy Dose
Estradiol valerate (EV)	4-5 days	Every 5 days	3-5 mg	4-8 mg every 5 days
Estradiol cypionate (EC)	5-7 days	Every 7 days	2-4 mg	3-6 mg every 7 days
Estradiol enanthate (EEn)	7-10 days	Every 7 days	4-6 mg	4-8 mg every 7 days
Estradiol undecylate (EUn)	14-21 days	Every 14-28 days	8-12 mg	10-20 mg every 14-21 days
Testosterone cypionate	7-10 days	Every 7 days	50-100 mg	N/A
Testosterone enanthate	7-10 days	Every 7 days	50-100 mg	N/A
Testosterone propionate	19-24 hours	Every 2-3 days	20-50 mg	N/A

Shorter intervals with smaller doses produce more stable levels and fewer side effects than longer intervals with larger doses. For trans women on EV, injecting every 5 days instead of every 7 reduces peaks and troughs. For trans men on T cypionate or enanthate, injecting every 7 days is standard, but some prefer every 5 days for more stable levels.

Note on injectable E2 doses: Recent multisite studies (2024-2025) indicate that the median effective weekly dose for achieving both target E2 levels (100-200 pg/mL) and T suppression (< 50 ng/dL) is around 4 mg (IQR 3-6 mg). Doses above 6 mg weekly often produce supraphysiologic E2 levels (> 200 pg/mL trough) in most people without additional T suppression benefit. Starting at 3-5 mg weekly and titrating based on blood tests is recommended.

Common Problems and How to Handle Them

Problem	Cause	What to Do
Sharp pain on insertion	Needle is dull or has barbs (can happen with reused needles or poor quality needles)	Stop, withdraw, use a fresh needle. Never reuse needles.
Bleeding after needle removal	Hit a small blood vessel (capillary)	Apply pressure for 1-2 minutes. This is common and not dangerous.
Bruising	Damaged capillary during insertion	Ice the area for 10-15 minutes. Bruising resolves in a few days.
Medication leaks out after injection	Injected too shallow; did not use Z-track; removed needle too quickly	Use Z-track technique next time. Apply pressure immediately.
Pain hours or days after injection	Muscle irritation from medication; needle trauma; injecting too fast	Ice the site. NSAIDs if needed. Switch to SC if persistent.
Redness, warmth, swelling at site (worsening after 24-48 hours)	Infection (possible abscess or cellulitis)	Seek medical attention. Draw a circle around the red area with a pen to track spread.
Lumps under the skin (oil deposits)	Injection into subcutaneous fat instead of muscle; not rotating sites	Massage the area gently. Rotate sites. These dissolve over weeks.
Sudden cough or chest tightness during/after injection	Rare: oil entering a blood vessel (pulmonary oil embolism)	Stop injecting. Seek emergency care if symptoms are severe.
Hit a nerve	Sharp, shooting pain or electric shock sensation on insertion	Withdraw immediately. Apply ice. The pain usually resolves. Avoid that site.

Infection Signs

Seek medical attention if you experience:

• Redness expanding beyond 1 inch from the injection site after 24-48 hours
• Increasing pain (not the usual soreness) after 24 hours
• Warmth at the site compared to surrounding skin
• Fever, chills, or general malaise
• Pus or unusual discharge from the site

Minor redness and soreness for 12-24 hours after injection is normal. If symptoms worsen after 48 hours or spread, it may be infected.

Oil Embolism

Pulmonary oil embolism is rare but serious. Symptoms include sudden coughing, shortness of breath, chest pain, or lightheadedness during or shortly after injection. If you experience these, stop injecting and seek emergency medical help. This can happen if a needle enters a vein and oil-based medication is injected directly into the bloodstream. Aspiration was traditionally recommended to check for this, but current evidence shows it does not prevent it reliably. Using proper technique (injecting into the correct site, not moving the needle around during injection) is the best prevention.

Needle Disposal

Method	How To
FDA-approved sharps container	Available at pharmacies or online. Seal when 3/4 full.
Heavy-duty plastic bottle (laundry detergent, bleach)	Temporary alternative. Tape the lid shut and label "SHARPS - DO NOT RECYCLE".
Pharmacy drop-off	Many pharmacies accept used sharps containers for disposal.
Hospital or clinic collection	Some hospitals have public sharps disposal kiosks.
Mail-back programs	Buy a pre-paid mail-back sharps container through a medical waste company.
Local needle exchange / SSP	Free disposal and often free sterile equipment.

Do not: Put needles in household trash, recycling bins, glass bottles, or plastic bags. This puts sanitation workers and family members at risk of needlestick injury.

Do not: Recap used needles. This is the most common cause of accidental needlestick among people who inject.

References

1. CDC. Safe injection practices. https://www.cdc.gov/injectionsafety/
2. UCSF Transgender Care. Injection guide. https://transcare.ucsf.edu/
3. WHO. WHO guideline on the use of safety-engineered syringes for intramuscular, intradermal and subcutaneous injections in health care settings. https://www.who.int/publications/i/item/9789241549820
4. American Medical Association. Aspiration before injection: no longer recommended. https://www.cdc.gov/injectionsafety/
5. TransHarmReduction. Injection safety guide. https://www.transharmreduction.org/