What are puberty blockers?

Puberty blockers are medications that delay or pause the onset of puberty. They are used to stop the physical changes that come with puberty, such as masculinization or feminization, especially for those who have just started or are about to start developing. These blockers can be taken instead of estrogen or testosterone if someone needs more time to decide whether to transition. However, they are only recommended for people who have not yet completed puberty.

Effects

The effects of puberty blockers are fully reversible. If you use them to delay puberty, you can stop taking them at any time and your natural puberty will resume. However, if you decide to start hormones like estrogen or testosterone instead, your body will then begin developing along that path instead.

Effects for AFAB people (assigned female at birth):

• Halted growth

• Halted breast development

• Halted body feminization

• Halted menstruation

Effects for AMAB people (assigned male at birth):

• Halted growth

• Halted deepening of voice

• Halted body masculinisation

• Halted genitalia development

Risks

General risks that come with taking puberty blockers include weight gain, hot flashes, headaches, and mood changes. Long-term use can have an effect on height increase, bone growth, bone density, and fertility, depending on when the treatment is started.

AFAB

For AFAB people, the primary available option to block puberty is a medication called Relugolix. Relugolix is a GnRH antagonist, which means it blocks the hormones responsible for triggering estrogen and testosterone production. Within 24 hours of taking it, estrogen levels drop to postmenopausal levels, effectively pausing puberty.

Obtaining blockers

There is currently only one retailer of Relugolix; you can purchase it here (https://opengatelabs.com/product/relugolix-capsules-40mg-100ct/). This product is a package of 100 pills, each being 40mg, but if you purchase a pill cutter to cut the pills into 20mg you can make your supply last twice as long. More information is in the dosing guide below.

AMAB

AMAB people have a much larger variety of choice when it comes to puberty blockers. The most reliable form are anti-androgens, also known as testosterone blockers, which are used to delay or suppress male puberty by blocking or reducing testosterone levels. Common anti-androgens include bicalutamide, cyproterone acetate, and spironolactone.

• 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 AMABs, 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.

Obtaining blockers

Here is a list of anti-androgens that can perform the role of puberty blockers.

Note: If you’ve already looked at the dosage information below, you might have noticed that each cyproterone pill contains 4 to 8 times more than the recommended daily amount based on age. That’s because cyproterone is effective at just 5mg to 10mg per day for testosterone suppression, which is much lower than what a single pill provides. So, if you’re planning to buy cyproterone, it’s a good idea to also pick up a pill cutter so you can divide the tablets into smaller, more appropriate doses. A single pack of 50 pills at 50mg each could last you 200 days or more, making it a very cost-effective option.

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 trans children aged 11 or younger. Because of this, we cannot ensure the safe use of puberty blockers 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 or feminizing changes. Unfortunately, if you live in areas with restrictive laws, you may not be able to access 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 puberty is still in the early stages between 12 and 13, so if you haven't started by then there’s no need to worry, since you have not finished puberty yet.