Injectable Estrogen

Overview

Injectable estradiol is a popular choice for DIY HRT and is increasingly prescribed. It provides high bioavailability, excellent T suppression (often enabling monotherapy), and requires less frequent dosing than pills or gel.

Estradiol Esters

Ester	Half-Life	Typical Dose	Frequency
Estradiol valerate (EV)	4–5 days	2–8 mg	Every 5 days
Estradiol cypionate (EC)	5–7 days	1–5 mg	Every 7 days
Estradiol enanthate (EEn)	7–10 days	3–8 mg	Every 7 days
Estradiol undecylate (EUn)	12–16 days	10–20 mg	Every 14–28 days

EEn availability

Estradiol enanthate (EEn) is significantly less available as a pharmaceutical product than EV or EC in the UK, most of Europe, and North America. It is more commonly sourced via homebrew. If you need a pharmaceutical option, EV or EC are more widely stocked.

Dosing Guidelines

Estradiol Valerate (EV)

Goal	Dose	Frequency	Notes
Starting	2–4 mg	Every 5 days
Typical	3–5 mg	Every 5 days
Monotherapy	4–8 mg	Every 5 days	Most people achieve T suppression at 4–6 mg
Maximum	8 mg	Every 5 days	Rarely needed; doses above 6 mg often produce supraphysiologic levels

Estradiol Cypionate (EC)

Goal	Dose	Frequency
Starting	1–3 mg	Every 7 days
Typical	2–4 mg	Every 7 days
Monotherapy	3–6 mg	Every 7 days

Estradiol Enanthate (EEn)

Goal	Dose	Frequency
Starting	3–4 mg	Every 7 days
Typical	4–6 mg	Every 7 days
Monotherapy	4–8 mg	Every 7 days

Monotherapy with Injections

One of the biggest advantages of injectable estradiol is that at sufficient doses, it can suppress testosterone without anti-androgens (monotherapy). This works because:

• High E2 levels signal the hypothalamus/pituitary to reduce LH production
• Lower LH means the testes produce less testosterone
• At E2 trough levels above ~200 pg/mL, most people achieve T < 50 ng/dL

Monotherapy dosing

For EV, most people achieve T suppression at 4–6 mg every 5 days. For EEn, 4–6 mg every 7 days. EC typically requires slightly lower dosing (3–5 mg every 7 days). Recent large studies (2024-2025) show the median effective dose is around 4 mg weekly, and doses above 6 mg weekly often produce supraphysiologic E2 levels without additional T suppression benefit. Check trough levels after 4–6 weeks and adjust accordingly.

Injection Technique

Equipment Needed

• Estradiol vial
• Syringe (1–3 mL, luer lock recommended)
• Needles: 18–23G for drawing, 25–27G for injecting
• Alcohol swabs
• Sharps container

Injection Sites

Site	Needle Length	Notes
Gluteal (buttock)	1–1.5 inches	IM; most common, steady absorption
Ventrogluteal	1–1.5 inches	IM; lower pain, good absorption
Thigh (vastus lateralis)	1–1.5 inches	IM; easy to self-inject
Subcutaneous (abdomen)	0.5–0.625 inches	SC; slower absorption but effective

Step-by-Step (IM)

1. Wash hands thoroughly
2. Clean the vial rubber stopper with an alcohol swab
3. Draw air into syringe (equal to your dose volume)
4. Inject air into the vial
5. Draw the correct dose volume
6. If using homebrew: Attach a 0.22 μm sterile syringe filter and push the solution through before attaching the injection needle. This removes bacteria, fungal spores, and particulates. (Not needed for sealed pharmaceutical vials.)
7. Change to injection needle
8. Clean injection site with alcohol swab
9. Insert needle at 90° angle (IM)
10. Do not aspirate (pull back plunger). Modern guidelines from the CDC, WHO, and AMA recommend against aspiration for IM and SC injections — it does not improve safety and adds unnecessary pain. If blood appears in the needle hub during insertion (rare), withdraw immediately, apply pressure for 1–2 minutes, and use a fresh needle at a new site.
11. Inject slowly
12. Withdraw needle, apply pressure
13. Dispose of needle safely in sharps container

Injection Frequency & Trough Levels

• Test at trough — right before your next injection (lowest point of your cycle)
• Target trough E2: 100–200 pg/mL (367–734 pmol/L) per guidelines (higher for monotherapy, typically 200–300 pg/mL)
• Target T: < 50 ng/dL (< 1.73 nmol/L)
• Test after at least 4 weeks on a stable dose
• Note: Some people achieve T suppression even with E2 < 100 pg/mL, and not everyone with E2 above 200 pg/mL achieves T < 50 ng/dL. Individual response varies significantly.

Pros & Cons

Pros	Cons
High bioavailability	Requires needles (fear of injections)
Excellent T suppression (monotherapy)	More complicated to do
Low VTE risk (no first-pass)	Requires sterile technique
Less frequent dosing	Injection site pain/swelling
Best E2:E1 ratio	Estradiol vials less commonly prescribed
Good for stubborn T	Can cause high peaks + low troughs

Common Problems

Problem	Solution
Pain at injection site	Use smaller needle (27G), warm the vial, inject slowly
Lumps (oil deposits)	Massage area, rotate injection sites
Post-injection bleeding	Apply pressure; use smaller needle
Air bubbles	Tap syringe and push out bubbles before injecting
Can't draw the solution	Inject air into vial first

References

1. UCSF Transgender Care. Estrogen: routes of administration. https://transcare.ucsf.edu/guidelines

2. WPATH (2022). Standards of Care, Version 8. https://www.tandfonline.com/doi/full/10.1080/26895269.2022.2100644

3. Hembree WC, et al. (2017). Endocrine Treatment of Gender-Dysphoric/Gender-Incongruent Persons. JCEM. https://academic.oup.com/jcem/article/102/11/3869/4157558