The Hidden Side Effects of Testosterone Therapy

If you’re undergoing testosterone replacement therapy (TRT) in the Phoenix metro area, you might be enjoying renewed energy and vitality. But what your doctor may not have emphasized is that TRT can silently raise your hemoglobin and hematocrit levels, essentially thickening your blood. This effect — a form of secondary erythrocytosis (high red blood cell count) — is a predictable yet underrecognized side effect of testosterone​. Understanding this hidden impact is crucial for your health. In this article, we’ll explore how testosterone therapy can boost red blood cell production, the biological mechanisms behind it (like increased erythropoiesis and suppressed hepcidin), and the symptoms and risks of those elevated levels.

We’ll also discuss what you can do about it, including therapeutic phlebotomy as a solution. Finally, we’ll spotlight how OptiVena Mobile Phlebotomy — a mobile lab service operating throughout Phoenix, Scottsdale, Tempe, Gilbert, Mesa, Chandler, Queen Creek, and surrounding areas — can provide at-home therapeutic phlebotomy for safe blood removal when needed.

Testosterone Therapy Can Raise Hemoglobin and Hematocrit

Testosterone’s positive effects (improved muscle mass, mood, libido, etc.) are well known. However, TRT also stimulates your body to make more red blood cells, often more than you actually need. As a result, some men on TRT develop elevated hemoglobin and hematocrit – meaning higher concentrations of red blood cells in their blood. In simple terms, the blood becomes “thicker.” Doctors sometimes call this testosterone-induced erythrocytosis or secondary polycythemia.

Why does this matter? High hemoglobin/hematocrit can increase blood viscosity (thickness), which in turn can slow circulation and cause a host of issues. Mild elevations might not cause noticeable symptoms, but significant increases can lead to headaches, dizziness, a ruddy complexion (red face), or high blood pressure. In severe cases, extremely thick blood can reduce oxygen delivery and trigger “hyperviscosity syndrome” – symptoms like blurred vision, ringing in the ears, chest pain, or weakness​. Over time, untreated high hematocrit elevates the risk of blood clots, which can result in venous thromboembolism, heart attack, or stroke. It’s serious stuff, and it’s essential to recognize that TRT can set this chain of events in motion.

Many patients aren’t initially aware of this side effect. Your provider might check your blood counts periodically, but not all doctors thoroughly explain this “thick blood” risk of testosterone therapy upfront. One reason it flies under the radar is that TRT-induced erythrocytosis often develops gradually and may not cause obvious symptoms right away.

You might feel great on TRT even while your hemoglobin creeps upward. Regular lab monitoring is key: guidelines typically recommend checking blood counts at baseline, 3-6 months into therapy, and then annually​.

In practice, about 5% to 15% (or even more, depending on age and dose) of men on TRT will develop elevated hematocrit that warrants intervention​. Older men and those on higher-dose injectable testosterone are at higher risk, as studies show hematocrit can rise in a dose-dependent manner and increases tend to be more pronounced in men over 60​. It’s not uncommon for hematocrit to start climbing within the first month or two of therapy and peak in the first year.

This means that what your doctor may not be telling you – but you should absolutely know – is that monitoring and managing your blood counts is a crucial part of safe testosterone therapy.

How Testosterone Increases Red Blood Cell Production

Why does testosterone therapy raise your hemoglobin and hematocrit? The answer lies in how testosterone interacts with your body’s blood-making machinery. Testosterone is a powerful stimulator of erythropoiesis, the process by which new red blood cells (erythrocytes) are produced in the bone marrow. Here are the key biological mechanisms involved:

Boosting Erythropoietin (EPO): Testosterone signals the kidneys to increase production of erythropoietin, a hormone that directs your bone marrow to manufacture more red blood cells​. Essentially, TRT can reset your body’s EPO and hemoglobin “set point” to a higher level. Shortly after starting TRT, studies have observed an initial surge in EPO levels that corresponds with rising red blood cell counts​.

Suppressing Hepcidin (Iron Regulator): Testosterone also lowers levels of hepcidin, a liver-produced hormone that normally limits iron availability​. Hepcidin is like the gatekeeper for iron: when it’s high, less iron is absorbed from your diet and more is locked away in storage. By suppressing hepcidin, testosterone frees up more iron in your bloodstream​. More available iron means your bone marrow has extra raw material to churn out hemoglobin and red blood cells. In one clinical trial, men on testosterone therapy experienced a 57% decrease in hepcidin levels over 12 months, along with significant increases in hemoglobin (8% rise) and hematocrit (4% rise)​.

Direct Bone Marrow Effects: Beyond EPO and iron, testosterone may have direct effects on bone marrow stem cells. Research indicates it can increase the number of progenitor cells that mature into red blood cells and even improve red blood cell survival​. Additionally, some testosterone is converted to estradiol (estrogen) in the body, which can aid hematopoietic (blood-forming) stem cell proliferation​. The combined effect is a robust signal for your body to produce blood.

In short, TRT creates a perfect recipe for more red blood cells: higher EPO (telling your marrow “make more”), more iron (fuel for building hemoglobin), and a stimulated bone marrow environment. This is great if you were anemic or had low red cell counts – in fact, testosterone was historically used as a treatment for anemia. But if you start with normal levels, TRT can push you into above-normal hemoglobin/hematocrit ranges.

The longer and higher the dose of therapy, the more your levels might climb. For example, one study found hematocrit began rising within one month of TRT initiation and continued to increase linearly over three months (and beyond), especially at higher doses​. Older men were more prone to large increases; in that study, 75% of men aged 60–75 on a moderate dose developed an elevated hematocrit, compared to 42% of younger men on the same dose​. Moreover, the route of testosterone can make a difference: intramuscular injections tend to cause larger spikes in hemoglobin than transdermal gels or creams​. (This is because injections deliver a higher peak dose into your system at once.)

It’s essential that your healthcare provider keeps an eye on those hemoglobin and hematocrit values. Typically, a hematocrit above ~50% or hemoglobin above ~18.0 g/dL will get your doctor’s attention​. Many clinics will actually pause or adjust testosterone therapy if hematocrit exceeds 52–54% (thresholds vary by guideline)​. At that point, action is needed to prevent complications.

Symptoms and Risks of Elevated Hematocrit

One tricky aspect of testosterone-induced erythrocytosis is that you might not notice any symptoms at first. A routine lab test may be the first tip-off that your hemoglobin or hematocrit is high​. However, as levels climb, the blood’s increased thickness (viscosity) can start to cause symptoms. It’s important to recognize these warning signs:

Headaches and Dizziness: One of the most common complaints. Thicker blood flows less easily, which can cause headaches, lightheadedness, or dizziness – especially if hematocrit creeps well above normal​. You might feel a pressure or fullness in your head that wasn’t there before.

Facial Redness or Flushing: Some men develop a ruddy complexion, red face, or flushing. You might notice your skin (especially face) looks more flushed or warm. This happens because high red cell mass increases blood volume and can make blood vessels more engorged.

Fatigue and Weakness: It sounds counterintuitive since more red blood cells should carry more oxygen, but extremely high levels can actually reduce oxygen delivery to tissues due to sluggish circulation. This can leave you feeling tired, weak, or easily fatigued​.

Shortness of Breath or Chest Pain: In serious cases, high hematocrit can strain the heart and lungs. Some people experience shortness of breath, difficulty breathing, or chest tightness (especially during exercise) when their blood is too thick​. This is a red flag that needs prompt attention.

High Blood Pressure: With more red cells packed into your bloodstream, blood pressure can rise. Your heart has to work harder to pump the viscous blood. New-onset or worsening hypertension in a person on TRT could be related to rising hematocrit.

Vision Disturbances and Ringing Ears: Blurred or double vision can occur because sluggish blood flow affects the tiny vessels in the eyes. Similarly, ringing in the ears (tinnitus) may appear. These are classic symptoms of hyperviscosity syndrome – when blood is so thick that it impairs microcirculation​.

Swelling or “Thick” Feeling: Some report a sense of fullness in the hands or feet, or mild swelling (edema). There are even case reports of lower extremity edema linked to high hematocrit on TRT​.

It’s worth noting that these symptoms are not exclusive to high hematocrit and could be caused by other issues. But in the context of testosterone therapy, they should prompt a check of your blood counts.

Without treatment, very high hemoglobin/hematocrit can lead to serious complications. The biggest dangers are blood clots forming in veins or arteries. Clots in leg veins (deep vein thrombosis) can cause pain and swelling, and if a clot travels to the lungs it causes a pulmonary embolism – a potentially life-threatening event. Thick blood can also contribute to clots in the arteries, raising the risk of heart attacks or strokes​. Additionally, elevated hematocrit is linked with increased risk of acute cardiovascular events in some studies​​, so it’s not something to ignore.

The good news is that if caught in time, testosterone-induced erythrocytosis is manageable and usually reversible. The main goal is to bring your hemoglobin and hematocrit back into a safer range, which we’ll discuss next. Just remember:  listen to your body and get those routine labs done. If you’re on TRT and experiencing unexplained headaches, lethargy, or shortness of breath, it’s wise to get your blood levels checked. It might just be your hemoglobin running high.

Managing Elevated Hematocrit from TRT

So, what should you do if your blood counts are rising due to testosterone therapy? There are a few strategies to keep your hemoglobin and hematocrit in check without sacrificing the benefits of TRT:

Adjusting the Testosterone Dose or Method: The first approach is often to modulate your TRT regimen. Your doctor might lower your dose or suggest spreading injections out to smaller, more frequent amounts. In some cases, switching from intramuscular injections to a transdermal gel or cream can help, since gels tend to have a lower impact on red blood cell production​. As one case showed, a patient who developed high hemoglobin and shortness of breath on injections had his levels normalize and symptoms resolve after switching to a topical testosterone​. Every patient is different, but the goal is to find the lowest effective dose that doesn’t push your hematocrit too high.

Address Contributing Factors: Certain factors can amplify erythrocytosis. If you smoke or use nicotine, quitting can help (smoking itself raises red blood cell count). Obstructive sleep apnea (common in men with low T and often coexistent) can also cause elevated hematocrit; ensuring your sleep apnea is treated (with CPAP, for example) is important​. Staying well-hydrated is a simple measure – dehydration can concentrate your blood and worsen lab readings, so drink plenty of water especially before blood tests.

Periodic Blood Donation: Many TRT patients are advised by their doctors to donate blood periodically as a way to reduce hematocrit. Donating a unit of blood (approximately one pint) removes a portion of your red blood cells, which in turn lowers your hemoglobin/hematocrit. For some men, giving blood every few months is sufficient to keep levels in a safe range. This can be a win-win: you reduce your health risk and help someone in need of blood. However, this approach isn’t always straightforward – blood donation centers have rules and limits. For instance, the American Red Cross requires donors to have a hemoglobin below 20 g/dL and allows standard donations only every 56 days. If your hemoglobin is extremely high or if you need to give blood more frequently than the donation center allows, they may defer you as a donor.

(Blood banks also might not accept donations that are done solely for therapeutic purposes or if they suspect an underlying medical condition causing high counts.) In short, not all TRT patients can rely on blood bank donations to manage hematocrit.

Therapeutic Phlebotomy: When donation isn’t an option or your doctor decides a more controlled approach is needed, therapeutic phlebotomy is the go-to treatment. Therapeutic phlebotomy is essentially the clinical version of blood donation — a controlled blood draw prescribed specifically to reduce your red cell count. A healthcare professional will draw off a set amount of blood (usually a pint, or 500 mL, but sometimes less) to bring your levels down.

The procedure is very similar to donating blood, except that the blood is typically discarded as medical waste rather than given to a blood bank (since it’s done for an underlying medical conditions and not for donation). Removing blood periodically forces your body to use up some of those excess red cells and iron, which lowers hemoglobin and hematocrit.

For someone on TRT with high hematocrit, this is a quick and effective fix: often a single phlebotomy can drop hematocrit by a few points. Your doctor will usually recheck your levels after phlebotomy to ensure it worked, and you might need to repeat the procedure on some schedule (e.g. every few months) if you continue TRT.

Therapeutic phlebotomy is a common and safe practice – it’s actually the same treatment people with polycythemia vera (a blood disorder causing high red cells) receive regularly. The main side effects can be mild lightheadedness or fatigue after the draw, but these are manageable (and often less troubling than the symptoms of untreated high hematocrit!).

Lifestyle and Follow-Up: Lastly, keep up with healthy lifestyle habits that support cardiovascular health. Exercise (within reason), maintain a healthy weight, and avoid excessive alcohol (as it can dehydrate you). Make sure to go to all follow-up appointments – you’ll want to regularly monitor your blood counts until they stabilize in a safe range. Never ignore a high lab value; work with your provider on a plan to bring it down.

The bottom line is TRT-induced high hemoglobin is treatable. It doesn’t mean you have to stop testosterone therapy entirely (in fact, many men continue TRT with periodic phlebotomy management). It just means you and your healthcare team need to be proactive. In the Phoenix area, there are convenient options to get therapeutic phlebotomy done without derailing your busy life – including services that come to your home.

OptiVena Mobile Phlebotomy: Therapeutic Phlebotomy At Home in Phoenix, AZ & Surrounding Cities

For men in the Phoenix metro dealing with elevated hematocrit from TRT, OptiVena Mobile Phlebotomy offers a convenient, professional solution. OptiVena is a mobile lab service that comes to you – whether you’re at home or at the office – to perform lab draws and therapeutic blood removal on-site. This means you no longer have to search for a clinic or hospital appointment (or wait in line at a lab) for something like a prescribed phlebotomy. If you’ve been googling for a “therapeutic phlebotomy near me” and feeling frustrated with limited options, OptiVena might be exactly what you need.

OptiVena’s therapeutic phlebotomy service is ideal for TRT patients who have been advised to reduce their hemoglobin levels. In fact, many of our clients come to us after being turned away from blood donation centers due to high hemoglobin or too-frequent donations. We understand how discouraging it can be to hear “you can’t donate right now,” especially when you need to get blood off for your health. That’s where our mobile phlebotomy service near you comes in – we fill that gap by providing therapeutic blood draws in a safe, controlled manner at your convenience.

Here are some key features of OptiVena Mobile Phlebotomy’s at-home therapeutic phlebotomy and why it stands out as an at home blood draw service near me for Phoenix-area residents:

Experienced, Certified Professionals: OptiVena’s mobile phlebotomists have 13+ years of phlebotomy experience and are nationally certified. You can trust that you’re in skilled hands. Drawing blood in a therapeutic setting requires expertise, and our team excels in providing a safe, comfortable experience every time.

In-Home Privacy and Comfort: We perform blood draw at home in the privacy of your own space. This means you can relax in a comfortable chair at home (or even at work) while we handle the procedure. It’s discreet and convenient – no public waiting rooms, no explaining to strangers that you’re getting a therapeutic phlebotomy. For those who value privacy or have anxiety about clinical settings, this is a huge benefit.

Fast, Flexible Appointments: Need it done soon? We’ve got you. OptiVena offers appointments as soon as the next day, and we operate Monday through Saturday to fit your schedule​. Lab facilities in Phoenix often don’t offer weekend therapeutic phlebotomy, but our mobile lab service can even come on a Saturday if needed. We strive to accommodate busy professionals and urgent needs – early morning appointments, next-day scheduling, and more are available.

Serving the Phoenix Metro: Whether you’re in Phoenix, Scottsdale, Tempe, Gilbert, Mesa, Chandler, Queen Creek, or nearby, OptiVena’s mobile phlebotomy service has you covered. We travel to homes and offices across the Valley. No need to commute or fight traffic to get your blood drawn; our phlebotomy team comes directly to you. This “phlebotomy service near me” truly means near you – wherever you are in the region! (Our standard service radius covers the East Valley and we can arrange visits to other areas as well, so nearly all Phoenix metro patients can take advantage.)

Seamless and Professional Service:  With OptiVena, the process is straightforward. All you need is a doctor’s order for the therapeutic phlebotomy (which indicates how much blood to remove and how often). Our staff will handle the rest. We bring all necessary equipment to perform a safe blood draw, following proper medical protocols. After the draw, we can either dispose of the blood per medical guidelines. Our focus is safety, compliance, and patient comfort. And because we’re a mobile service, you get one-on-one attention without the rush of a busy clinic. We also ensure your lab work and records are handled properly – if needed, we can deliver any samples to a lab or provide documentation to your physician.

By using a service like OptiVena Mobile Phlebotomy, TRT patients can manage high hematocrit effectively without interrupting their daily routine. Imagine not having to take a half-day off work to sit in a lab waiting room; instead, a qualified mobile phlebotomy professional arrives at your door at a scheduled time, the draw is done in typically 25–45 minutes, and you’re free to go about your day. It’s stress-free and personalized. This level of convenience is especially valuable if you require repeated phlebotomies (for instance, some patients might need them every 2–3 months to maintain safe levels). OptiVena makes it as easy as getting a mobile blood test – truly lab services on your terms.

In summary, if you’re on testosterone therapy in the Phoenix area, keep an eye on your blood counts. It’s one aspect of TRT that your doctor may not have highlighted, but it’s critical for your well-being. Elevated hemoglobin and hematocrit can pose risks, but with proper monitoring and management – from adjusting your TRT regimen to removing blood when necessary – you can continue therapy safely. OptiVena Mobile Phlebotomy is here to support you in that journey, offering a reliable and convenient therapeutic phlebotomy service when you need it.

Don’t let “thick blood” undermine the benefits of your testosterone therapy. With the right knowledge and resources, you can enjoy the advantages of TRT while keeping your heart and blood vessels happy.

For more information or to schedule a mobile therapeutic phlebotomy appointment, you can reach out to OptiVena Mobile Phlebotomy and get expert help right at your doorstep. Your health is your wealth – stay informed, stay proactive, and take advantage of modern solutions like mobile lab services to optimize your TRT experience.

Sources used in this article:

The Blood Project. Testosterone Therapy and Erythrocytosis – Clinical Case Study. Available at: https://www.thebloodproject.com/cases-archive/testosterone-therapy-and-erythrocytosis-2

American Urological Association. Guideline: Evaluation and Management of Testosterone Deficiency. Available at: https://www.auanet.org/guidelines-and-quality/guidelines/testosterone-deficiency-guideline

Roy CN, Snyder PJ, et al. Association of Testosterone Levels With Hemoglobin and Erythropoiesis in Men: A Controlled Study. PubMed (NIH), 2014. Available at: https://pubmed.ncbi.nlm.nih.gov/24674841

Bachman E, Travison TG, et al. Testosterone Suppresses Hepcidin in Men: A Potential Mechanism for Testosterone-Induced Erythrocytosis. PMC. Available at: https://www.ncbi.nlm.nih.gov/pmc/articles/PMC4022090

Bhasin S, Woodhouse L, et al. Testosterone Dose–Response Relationships in Healthy Young Men. Journal of Clinical Endocrinology & Metabolism. Available at: https://academic.oup.com/jcem/article/93/3/914/2597516