What is estrogen?

Estrogen is a group of sex hormones responsible for the development of female physical traits. It is important during female puberty and for regulating the reproductive system. Estradiol, often abbreviated as E2, is the most potent and commonly referenced form of estrogen, and in this guide, the terms “estrogen” and “estradiol” may be used interchangeably.

Estrogen is responsible for many traits typically associated with female puberty, including wider hips, breast development, reduced muscle mass, shorter stature, softer skin, and less body hair. While both men and women produce estrogen, women generally have much higher levels, which is why they experience feminizing changes during puberty.

What are anti-androgens?

Hormone therapy for transgender girls involves a few important complexities. Typically, trans girls take two medications rather than just one: estrogen and an anti-androgen. Anti-androgens, also known as testosterone blockers, are used because many trans women don’t naturally reach high enough estrogen levels to fully suppress testosterone on their own.

When only one medication is used to treat a condition, it’s called monotherapy. In the context of HRT, monotherapy is generally only possible when estrogen is administered via injections, which are potent enough to suppress testosterone without the need for a blocker. Other forms, like pills or gels, usually aren’t strong enough on their own, which is why anti-androgens are commonly included in HRT regimens.

Additionally, some people choose to incorporate a hormone called progesterone later in their transition, often after being on HRT for at least two years. Progesterone may support further breast development, and I’ll go into more detail on that below.

For anti-androgens, you can use the following three medicines: bicalutamide, cyproterone acetate, or spironolactone. When you use these medications in combination with estrogen, it enhances the anti-androgen's effects.

• Cyproterone acetate (cypro) is an anti-androgen that helps stop the body from producing testosterone, which prevents further masculinization. It works mainly by blocking testosterone from being made in the testicles and stopping them from interacting with androgen receptors. It also reduces testosterone by blocking LH, a hormone that tells the testicles to make testosterone. Even though it's not the absolute strongest option, cyproterone is the most commonly recommended anti-androgen because it's effective, affordable, and does not carry as many risks as bicalutamide.

• • Bicalutamide is an anti-androgen that blocks the effects of testosterone, but it doesn’t stop your body from producing it. This means you won’t masculinize, even though your testosterone levels will still be in the male range. Bicalutamide is the second most recommended anti-androgen. It's actually more powerful and effective than cyproterone, but we rank it lower because despite its wide availability, it's more expensive and doesn't show up well on standard blood tests, so it's more unreliable. That said, it does its job well as an anti-androgen.

• • Spironolactone (spiro) is a relatively weak anti-androgen that reduces testosterone production. It tends to be more effective for early-puberty trans girls, since their testes are not fully developed and naturally produce less testosterone. The main advantage of spironolactone is its low risk of serious side effects, making it a safer option for some. It's ranked as the third most recommended and third most effective anti-androgen due to its limited strength and high variability in how people respond to it. While it's slightly more expensive, if you have access to cyproterone or bicalutamide, those are generally better options. If those are available to you, we recommend not choosing spironolactone.

Progesterone

Progesterone is a sex hormone found in both males and females, but it plays a bigger role in women, especially in the menstrual cycle, reproduction, and breast development. While men naturally have small amounts, trans women sometimes take progesterone for potential benefits like improved breast growth. Some trans women also report increased libido when using it orally, though studies haven’t found strong evidence to support this. When starting progesterone, it’s best to wait until you’re in the middle stages of breast development, as starting too early may slow or stunt growth. This idea is supported by several pediatric endocrinology sources, though more scientific research is still needed. When taken at the right time, progesterone can help develop fuller, rounder breasts.

Effects

When starting HRT with estrogen, you can expect to see various physical changes over time. A general timeline is provided below, but the speed and extent of these changes can vary based on factors like age and dosage. It’s important to understand that estrogen is more effective when started before or during male puberty. Once male puberty is complete and your bones have fused, estrogen cannot undo skeletal changes such as jaw or shoulder structure, nor can it build new bone in the way testosterone does.

For those who have already completed male puberty, certain changes like voice feminization or typical female bone structure will not occur. However, you can still expect some feminizing effects, such as the development of breasts, softer skin, and increased fat in areas like the thighs and hips.

Irreversible effects:

• • • Breast growth

    • Decreased genitalia size

Reversible effects:

• • • Becoming more emotional

    • Change in posture

    • Softened skin

    • Reduced facial hair

    • Reduced body hair

    • Decreased skin oiliness

    • Decreased sweating

    • Decreased acne

    • Decreased muscle mass

    • Decreased strength

    • Feminine fat redistribution

Added irreversible effects if you have not finished male puberty

• • • Feminine voice (reversible)

    • Feminine facial structure

    • Widened pelvis

    • Shorter height than male family members

    • Smaller shoulders than male family members

    • Smaller ribcage than male family members

Risks

As with any medication, taking estrogen comes with some potential risks. However, these risks are extremely mild compared to those that come with testosterone usage. It is very difficult to overdose on estrogen due to its lack of potency, although you should still avoid taking extremely large amounts over a long period of time. There is no risk associated with underdosing estrogen (other than not experiencing its full effects, of course).

General risks that come with taking estrogen include loss of fertility, blood clotting issues (deep vein thrombosis, stroke, pulmonary embolism, etc.), decreased thyroid, liver, and kidney function, and breast cancer, while minor risks include mood swings. However, it is important to note that these risks (not including loss of fertility) apply to anyone with high levels of estrogen in their body, not just transfeminine people. Additionally, risk levels differ depending on the method of administering estrogen.

Methods of taking estrogen

There are two main methods of administering estrogen: injections and pills. Many transfems have had positive results with other methods, such as gels, patches, sprays and droppers, however, these methods require regular blood testing to use safely. Gels and patches are compatible with HRT if blood testing is done regularly, while sprays and droppers are significantly less common and have very little evidence to suggest they work. In this guide, we will only go over pills and injections.

Injections

When it comes to injections, there are two main approaches: monotherapy (estrogen only) or non-monotherapy (estrogen plus anti-androgens). This flexibility is a major advantage, since injections can often eliminate the need for anti-androgens, making them one of the most cost-effective methods of HRT. Injections are also the most potent and effective way to take estrogen, typically requiring dosing only once every 7 to 14 days, depending on the type of estradiol ester used.

There are several injectable estradiol formulations available, including estradiol valerate, enanthate, cypionate, undecylate, and benzoate, among others. If you’re wondering which to choose, we recommend estradiol enanthate, cypionate, or undecylate, since these esters are longer-acting and require less frequent injections compared to shorter-acting options like valerate or benzoate.

Due to their convenience, cost-effectiveness, and high potency, injections are widely considered the most recommended method for delivering estrogen. The main downside, of course, is the need to use needles, which can be intimidating for some. If this is a significant obstacle for you, consider trying pills instead.

Pills

When using estrogen pills, you’ll need to take them alongside anti-androgens, and typically multiple times a day. This is because pills don’t raise estrogen levels high enough on their own to suppress testosterone. There are three types of estrogen pills: hemihydrate, 17-beta, and valerate. However, only hemihydrate and valerate pills are commonly sold, so you don’t need to worry about 17-beta. It’s important to note that valerate pills are less potent, so you’ll need to take more of them to achieve the same effect as hemihydrate pills.

For these reasons, pills are considered the second-best method for taking estrogen. While more expensive and less convenient than injections, they are an effective and accessible alternative.

Administering estrogen

How to take pills

There are two main ways to take estrogen pills: orally or sublingually. Taking them orally means swallowing the pill like any regular medication. Taking them sublingually means placing the pill under your tongue and letting it dissolve.

Why take it sublingually? Because it provides higher estradiol levels. Unlike oral swallowing, the sublingual method allows the estrogen to be absorbed directly into the bloodstream through the tissues under your tongue, avoiding some of the breakdown that happens in your digestive system. This means you can achieve effective hormone levels with fewer pills.

No matter which method you choose, it’s best to split your dose evenly throughout the day. For example, instead of taking 6mg all at once, take 3mg every 12 hours. This helps keep your estrogen levels more stable throughout the day, which may lead to better results.

How to inject

There are two methods of injection that you can use: intramuscular (IM) or subcutaneous (subq).

• IM needles inject directly into the muscle. These needles are around 1 inch long and with a wider diameter than subq needles. The pros of this type of injection are that the needle’s larger size makes the injection process fairly quick. The cons are that it can be intimidating and slightly painful when you start out, and the wider size of the needle makes your testosterone vial more susceptible to coring (more on that later).

• IM injection video: https://youtu.be/IrHgX-2qrjs 

• IM injection written instructions: https://fenwayhealth.org/wp-content/uploads/MG-6_TransHealth_InjectionGuide.pdf

• Subq needles inject right beneath the skin into fatty tissue. They are around ½ to ⅝ inches long and much narrower and finer than IM needles. The pros of this type of injection are that it is easier, less intimidating, less susceptible to coring, and almost always painless. The cons are that due to the small size of the needle, it can take longer to draw and inject the testosterone.

• Subq injection video: https://youtu.be/APSPbpqefKw

• Subq injection written instructions: https://www.med.umich.edu/1libr/NursingUnits/Giving_Subcutaneous_Injection.pdf

(Author’s note: I personally recommend subq injections, especially for people with a fear of needles. I was very nervous when I performed my first injection, but the small size of the needle and the lack of pain helped ease my fears. If you mess up your first injection, it’s totally fine - in fact, most people do! The more injections you perform, the less scary the process will be.)

To prevent bleeding and oil leakage, keep the needle in your skin for 30 seconds after you finish injecting, while maintaining pressure on the plunger. Apply firm pressure to the injection site with toilet paper or a similar material for about 10 seconds after removing the needle. This same technique also helps prevent oil leakage from the injection site.

All injection supplies can be found in our supplies list.

When it comes to injection risks, there are three main things you need to watch out for.

1. Injecting into a vein (IM only): If you notice any blood leaking out or entering your syringe while doing an IM injection, it means you’ve hit a vein. This is not common if you inject in the correct area, but if it does happen it’s important not to panic. Simply remove the needle, apply pressure onto the injection site with toilet paper or a similar material, and then redo the injection with a new spot. The bleeding will quickly stop, so you shouldn’t be worried about bleeding out.

2. Vial contamination/coring: This can occur when drawing testosterone from your vial into the syringe. To draw from the vial, you need to stick the needle through the rubber seal on the vial. If your needle is large enough, it can break the rubber seal and cause rubber to break off into the oil. This is called coring, a major safety risk to DIYers.

• • • If you’re doing subq injections and using a small needle, coring is extremely rare. However, if you are using a larger and wider IM needle, specifically between 18G and 25G, it may be a good idea to eliminate the risk of coring by using a small needle to draw and then switching to a larger needle to inject.

    • If your rubber seal breaks or you see suspicious-looking particulates floating in your vial, you will unfortunately have to dispose of it and purchase another. Saving money on vials is not worth the risk of severely damaging your health. If you have questions about the quality of your vial, consult the r/TransDIY reddit forum.

3. Finally, please make sure to cycle through different injection spots. If you inject into the same spot every week, you can develop scarring and become unable to inject there in the future.

After injections, needles become a biohazard and must be placed in a container that keeps them safely stored until they can be disposed of. In hospitals, these are known as sharps containers. It is not necessary to buy an official medical sharps container to store your syringes and needles; simply keep them in a single container such as an empty bleach/detergent jug, milk carton, or plastic tupperware. When the container gets full, throw it away in a trash can or dumpster that you are sure your parents will not check the contents of, preferably not near your home. Do not attempt to recycle used needles and/or syringes.

Storing vials

Estrogen vials can last up to three years when placed in standard room temperature. Storing them in cold temperatures or refrigerating them can cause the estrogen to crystallise. Crystallised estrogen is cloudy and contains small needle-like crystals that cause pain when injected. If you suspect your vial has crystallised, place it in a plastic bag and then submerge it in a bowl of water. Gently heat the water to around 90 - 100°F (32 - 38°C), and you should see the oil inside begin to clear. Avoid overheating the water, and do not use a microwave. It’s fine to keep your vial in slightly warm conditions over time, such as inside a backpack, but not too warm (for example, outside in 80°F weather).

Where to buy

To purchase estrogen, you'll typically use online pharmaceutical stores or homebrew websites. We’ve included the country of origin for each source in case you prefer ordering from a market closer to you, since shorter distances often mean faster delivery times.

Be sure to check out these curated HRT source lists, which are regularly updated and include options for estrogen, anti-androgens, and more:

• DIY HRT Market (https://diyhrt.market/)

• HRT Cafe (https://hrtcafe.net/).

Note: The sources listed are international, meaning they ship to most countries regardless of where you're located. For example, if you're in the UK and order from a Canadian source, your package should still arrive without issue. Also, estrogen is not a controlled substance, meaning it’s legal to purchase and import, so the risk of it being seized by customs is very low.

Below are lists of estrogen sources you can buy from. While the products may all seem similar, you should still explore and make a decision based on price vs. concentration and reviews. These sources are all well known and community trusted, and their vials are tested and verified as free of contaminants.

Injections

Pills

Dosage

Calculating injection doses

When you receive an estrogen vial, you’ll see labels like "40mg/mL" or "400mg/10mL." These indicate how much estrogen (in milligrams) is dissolved in the total volume of oil (in milliliters). For example, if the vial says "40mg/mL," it means there are 40 milligrams of estrogen in each 1 milliliter of oil. Most vials contain 10mL of liquid, so multiplying 40mg by 10 gives you a total of 400mg of estrogen in the full 10mL vial, which is the same as a label that says "400mg/10mL."

The formula for calculating how much estrogen you need to put in your syringe is [Dosage] / [Estrogen per mL] = [Syringe Millimeters]. For example, if you wanted to do a dose of 5 mg and your vial says “40 mg/mL”, you would divide 5 mg by 40 mg/mL to get 0.125 mL. This is how much estrogen oil you would draw up and inject to get 5 mg in your body.

One important term to understand is the concept of deadspace. Deadspace is the small amount of fluid that remains trapped between the syringe and the needle after an injection. This leftover fluid slightly reduces how long your vial will last, since a small extra amount is used with each shot. The lower the dead space, the longer your vial will last. It’s typically measured in microliters (μL), where 1 μL = 0.001 mL.

How long will your vial last?

If you want to calculate how many injections you can do with your vial, use this formula:

Make sure that for total deadspace you convert the microliters into millilitres (multiply the uL by 0.001)

Recommended dosage

The following dosage charts are based on age. If you're going through puberty faster than your male peers, we recommend that you increase your dosage of estrogen to 1-2 years above.

Notice that for injections there is dosage information for two different regimens: you can choose to inject once every 7 days or once every 10 days.

(Author’s note: I personally choose to inject every 10 days so that I have to do less injections. You can choose either option; both are equally effective.)

11 years or younger: There are currently no established HRT dosage guidelines for AMAB trans children aged 11 or younger. Because of this, we cannot ensure the safe use of hormone replacement therapy for individuals in this age group. If you are 11 years old or younger, please do not attempt DIY HRT.

If you live in a trans-affirming area, consider asking your primary care provider about puberty blockers if you wish to pause current or future masculinizing changes. Unfortunately, if you live in areas with restrictive laws, you may not be able to access hormone therapy or puberty blockers through official medical channels. If you're considering DIY HRT, it's strongly advised to wait until you're at least 12 years old. Keep in mind that male puberty typically begins around ages 12 to 13, so if you haven't started estrogen by then there’s no need to worry, since your puberty likely hasn’t started yet.

Self-care

To get the most out of taking estrogen, it's necessary to take care of your body and put in consistent effort. Simply taking HRT without supporting lifestyle changes won’t lead to dramatic results. One important factor is eating a healthy amount of food. Estrogen relies on body fat to create feminine features like breast development and typical female fat distribution. Having some body fat is essential for these changes. Also, not eating enough can negatively affect your endocrine system and overall health, so please make sure you're eating regularly and focusing on a nutritious diet.

Note: One interesting fact is that fat cells take around seven years to die and regenerate. This means that when you start estrogen, your most recently created fat cells will appear in a female pattern, while the fat cells you form right before starting estrogen will take seven years to regenerate and appear in a female pattern. Because of this, it will take up to seven years for your body fat to be fully redistributed in a female pattern.