Any time we take any medication, whether that be a compound, chemical, or food, we want to make sure that it’s as safe as it can possibly be for us. As much time and energy as we put into our health, we want to ensure that it stays that way.

And, of course, taking any kind of medication towards gender transition is no different. Understandably, people want to be sure that whatever they take will respond well with their bodies and not interact with anything else they are taking, including prescription medication, over-the-counter medicines, or even homeopathic remedies.

You are likely to have the same concern with the foods you eat and the drinks you drink, the air you breathe. You just want to keep your body as healthy as possible.

It’s no surprise, then, that people who are thinking about transitioning are frequently asking:

  • Is my hormone replacement therapy—my HRT—going to be okay? 
  • Is it safe for me to take my HRT in addition to my current medications? 
  • Do you have insight into this compound I’m drinking?
  • What is your guidance on the homeopathic remedy I’m using? 
  • What about my nutritional supplements or vitamins? 
  • What are the HRT drug interactions? 
  • Is there anything I should be concerned about regarding oestrogen or testosterone interactions?

You may rest easy knowing that you’re not alone in asking these questions. We all want the assurance that what we’re doing is safe and won’t negatively affect our bodies now or in the future.


The Differences Between Medicines

To put it simply, there are two kinds of medicines we use in healthcare:

The first is a compound that we make in the lab. This medication is designed to interact with a specific human body process, such as lowering cholesterol or blood pressure, dilating (opening) blood vessels, killing germs, or eliminating fungus. We create this type of chemical compound in a laboratory with a specific action in mind.

The second is another type of medicine, which we call bioidentical medicines. These are a complete copy of what our bodies already produce, and hormones are a great example of this. 

Let’s use your thyroid gland as an example. Thyroid hormone is a hormone that regulates your body’s metabolic rate, affecting heart, muscle, and digestive function and more.

Suppose your body isn’t producing enough thyroid hormone. In that case, you can take a replacement thyroid hormone, and it’s exactly the same hormone that your body should be producing, but it isn’t for many reasons. For your thyroid hormone levels to be at an optimal level, you will need to take a tablet that consists of thyroid hormone, it is identical to your natural hormone.


Bioidentical Oestrogen and Testosterone

The same is true for bioidentical oestrogen and testosterone—they are both bioidentical medicines. If you don’t have ovaries or aren’t producing enough oestrogen, you can take oestrogen as a medicine. And, because it’s bioidentical, you’re merely replacing the oestrogen that your body should have produced for you but didn’t.

Testosterone works the same way. As a bioidentical hormone, it just substitutes for the testosterone that your body should have produced. You can take replacement testosterone if you don’t have testicles or if your testicles aren’t making enough testosterone.


Oestrogen and Testosterone Interactions

The fact that HRT is bioidentical is both exciting and encouraging. Taking oestrogen simply replaces the hormone while making you look and feel like someone whose ovaries produce adequate oestrogen. If someone with ovaries produces that hormone naturally, then taking that hormone as a tablet, medication, or injection has the same risk. The same is true for testosterone; it’s bioidentical, and we’re merely replacing it. 

Suppose someone with testicles produces testosterone in a safe manner, and it’s interacting with the body and any other medicine in a safe manner. In that case, it’s quite safe for you to have that testosterone. It’s just that perhaps you don’t have testicles or are not producing enough, and you need to have that testosterone by replacement. 

So, what are the oestrogen interactions or testosterone interactions?

Simply put, if you wouldn’t have interactions with oestrogen and testosterone, your risk isn’t any greater using bioidentical hormone replacement therapy as someone who naturally produces it.


HRT Drug Interactions

Some people worry that taking HRT hormone replacement therapy is harmful or risky. Or perhaps that it will interact with other medications. It’s actually extraordinarily safe due to the bioidentical nature of these hormones.

We’re simply providing you with the identical hormone profile as your cisgender counterpart and the one that corresponds to your gender identity.

Additional examples of bioidentical hormones are puberty blockers, GnRH agonists, or gonadotrophin-releasing hormone agonists. It’s the same hormone that your brain produces. It’s the feedback loop that prevents you from producing too much testosterone or oestrogen.

It’s safe because it’s another form of the bioidentical hormone. It simply feeds into your system in the same way that it feeds into the systems of everyone else who produces these hormones naturally. We just give you enough to turn off your oestrogen, progesterone or testosterone production.


Hormone Blocking Chemical Compounds vs Bioidentical Hormones

If you’re a trans woman not taking the puberty blocker injection or implants, which are bioidentical, you may take medications such as Spironolactone, Finasteride, Cyproterone Acetate, or Bicalutamide. These medications are the other type of anti-androgens which are chemical compounds rather than bio identical hormones.

We have to be very careful that these medications work well with your body. Therefore blood tests to evaluate your kidneys and liver may be required. We also need to be cautious if you’re taking any other medications, such as heart or liver medications or any other prescriptions that may have an adverse effect on your liver. Because these drugs are chemical substances, they are different. We must be more vigilant in ensuring that they safely interact with your body.

Whereas bioidentical hormones, such as puberty blockers, oestrogen, and testosterone, are identical to what your body would make, and they are just as safe for you as they are for a cisgender person who produces them naturally.


How Do I Start HRT?

You’ll learn how hormone therapy can help you reach your transition goals during an Information Gathering Session with one of our gender specialists.

If hormone therapy is right for you, you’ll receive your first prescription via post or direct from your choice of pharmacy. Alternatively, we can send a treatment summary to your doctor, who will provide you with your prescription. Every three months, we’ll review your treatment to ensure it’s working for you. Every six months, we recommend a wellbeing review to ensure you’re in tip-top shape. Whether you want to fully medically transition or achieve minor masculinisation or feminisation with microdosing—we can go at the pace that suits you. 

It’s important to remember that you’ll need to take hormones for as long as you want the gender-affirming benefits to last. Certain procedures, on the other hand, will result in a reduction in your dosage. We want you to feel confident that your treatment and progress are exactly right for you.



  1. Drug development: the journey of a medicine from lab to shelf | The Pharmaceutical Journal
  2. Endocrine Facts & Figures | Endocrine Society


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Gender-affirming hormone therapy: Starting HRT and what to expect


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