Testosterone Side Effects in Trans Men and How to Stay Safe
Testosterone is mostly safe when used at the right dose with regular monitoring. Knowing the common side effects and the ones to watch closely helps you prevent problems early.
Key points
- Common effects include acne, oily skin, hair thinning, weight gain, lower good cholesterol, and vaginal dryness and thinning.
- The effect that needs blood test monitoring is thickened blood (high haematocrit), which can be managed by adjusting the dose or form of medicine.
- Going above the target dose won't make you masculinise faster; it adds risk. Follow up with a doctor, and don't buy and inject it yourself.
"Doctor, I've been injecting for three months and my face is covered in acne. Should I stop?" I hear this question very often from trans men who have just started hormones. The good news is that most testosterone side effects can be managed without stopping, as long as you recognise them early and follow up with your doctor regularly.
First, it's important to separate the "intended effects", such as a deeper voice, facial hair and periods stopping, from the "side effects" that need care. Read the timeline of desired changes in masculinising hormone therapy (FTM).
Common side effects and how to manage them
Acne and oily skin
These are common in the first year, especially on the face, back and chest, and usually improve once the body adjusts after 1–2 years. In the meantime:
- Wash your face with a gentle cleanser, and use topical treatments containing benzoyl peroxide or a retinoid as advised.
- If acne is severe or scarring, see a doctor; you may need oral medication.
- Injections spaced too far apart can cause big swings in levels and flare acne; adjusting the interval can help.
See more in hormonal acne.
Male-pattern hair thinning
This happens in people with a genetic tendency, because testosterone is converted to DHT at the hair follicles. Options include minoxidil and DHT-lowering medicines, but DHT blockers may reduce some desired changes, so discuss timing with your doctor (see finasteride).
Weight, cholesterol and blood pressure
Muscle increases along with appetite. Good cholesterol (HDL) usually falls, and triglycerides and blood pressure may rise slightly. Exercise, a sensible diet and scheduled monitoring help prevent heart disease in the long term.
Vaginal dryness and lower abdominal pain
As estrogen falls, vaginal tissue becomes thinner, which can make sex painful and urinary tract infections more likely. Some people have intermittent cramping in the lower abdomen. Your doctor may recommend lubricant, low-dose topical estrogen cream (which doesn't reduce masculinisation), or look for other causes if the pain is significant.
Mood and sleep
Early on, some people become more irritable and their sex drive rises sharply; most adjust over time. With injections, levels falling before the next dose can cause fatigue or low mood. Weight gain can lead to snoring or sleep apnoea.
Acne and oily skin
- Most common in year one; improves in 1-2 years
- Topical treatment as advised; see a doctor if severe
Male-pattern hair thinning
- Occurs in those genetically prone
- Discuss timing of minoxidil or DHT blockers with your doctor
Weight, lipids, blood pressure
- HDL often falls
- Exercise, diet, regular checks
Vaginal dryness, pelvic pain
- Painful sex, easier infections
- Lubricant or local oestrogen cream
Mood and sleep
- Irritable early on
- Weight gain may worsen snoring
Side effects that need blood test monitoring
Thickened blood (erythrocytosis)
This is the most important one. Testosterone stimulates the bone marrow to make more red blood cells, and if the blood becomes very thick, the risk of clots may rise.
- Factors that increase risk include high doses, injections with high post-injection peaks, smoking, sleep apnoea and living at high altitude.
- If haematocrit is above the threshold, doctors usually reduce the dose, lengthen the interval between injections or switch to gel, and look for contributing causes.
- Don't donate blood to "drain" it yourself without talking to your doctor.
Liver values, lipids and glucose
Injections and gels have little effect on the liver, but regular checks are still worthwhile, especially if you drink alcohol or use bodybuilding supplements (see steroids and PEDs).
A typical monitoring schedule
| Time | What is checked |
|---|---|
| Before starting | CBC, liver values, lipids, glucose, blood pressure, weight, pregnancy test |
| First year, about every 3 months | Testosterone level, haematocrit, blood pressure, symptoms and side effects |
| After the first year, every 6–12 months | Testosterone, haematocrit, lipids, glucose, and screening for the organs you have |
Details on preparation and when to have blood drawn are in blood tests before starting gender-affirming hormones.
Why you shouldn't buy injections yourself or increase the dose
Many people believe that the more you inject, the faster you masculinise. In reality, once your level is in the typical male range, increasing the dose doesn't speed up facial hair or voice changes. It increases acne, thick blood and mood swings, and some of the excess testosterone is converted to estrogen, which can bring periods back or cause spotting. Buying from non-standard sources also risks counterfeit products and infections from injecting.
Signs you need a doctor urgently
- A severe headache, blurred vision, a dark red face or difficulty breathing
- Chest pain, swelling and pain in one leg, or weakness in an arm or leg (call 1669, Thailand's medical emergency number)
- Vaginal bleeding after periods have stopped for a long time
- Severe lower abdominal pain or fever
- Very low mood, or thoughts of harming yourself or others (call 1323, Thailand's free mental-health hotline; Thai language, ask for English support)
Attentive follow-up at Dr. Kris Clinic
At Dr. Kris Clinic, I care for trans men from the start of treatment, with scheduled blood tests, dose or form adjustments when side effects arise, and care for related issues such as acne, mood and sexual health, at the clinic in Surat Thani and online, with English-speaking consultations available. If you have had your ovaries removed, read do trans men still need hormones after removal of the ovaries?
Medicines and services your doctor may consider
Prices are per pack. Every medicine is prescribed only after a doctor's assessment; your doctor will advise whether it suits you. See all medicines & services
Want help with this? Three simple steps
Reading is a good start. When you are ready, check where you are, see how a consultation works, then book a time that suits you.
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3Book with the doctorPick a time online or message us on LINE. Come on your own or with your partner. Payment confirms the booking.Book online →Self-checks are a guide only and do not replace a doctor's assessment. Outcomes vary from person to person, depending on the severity of symptoms, the complexity of the problem and other factors.
Start hormones safely
Assessment, blood tests and follow-up with a judgement-free doctor, in line with WPATH SOC-8.
Every medicine and service requires a doctor's assessment first.
Frequently asked questions
I have a lot of acne after starting testosterone. Should I stop?
Usually you don't need to stop. Acne often improves after the first year. Meanwhile it can be treated as normal, and your doctor may adjust the interval or dose to keep levels steadier.
My blood test shows thick blood. Is that dangerous?
Mild elevation can usually be managed by adjusting the dose, lengthening the injection interval or switching to gel. Very high levels raise the risk of clots, so see a doctor and don't increase your dose yourself.
My periods came back even though I'm still injecting. Why?
It may be because the dose is too low, injections are too far apart or missed, or the dose is so high that excess is converted to estrogen. Get your hormone levels checked, and if bleeding returns after a long gap, other causes need to be investigated too.
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References
- Hembree WC, et al. Endocrine Treatment of Gender-Dysphoric/Gender-Incongruent Persons: An Endocrine Society Clinical Practice Guideline. J Clin Endocrinol Metab. 2017;102(11):3869–3903.
- Coleman E, et al. Standards of Care for the Health of Transgender and Gender Diverse People, Version 8. Int J Transgend Health. 2022;23(Suppl 1):S1–S259.
- Madsen MC, van Dijk D, Wiepjes CM, et al. Erythrocytosis in a Large Cohort of Trans Men Using Testosterone: A Long-Term Follow-Up Study on Prevalence, Determinants, and Exposure Years. J Clin Endocrinol Metab. 2021;106(6):1710–1717.
- Irwig MS. Testosterone therapy for transgender men. Lancet Diabetes Endocrinol. 2017;5(4):301–311.
This article is for education and does not replace diagnosis or treatment by a doctor. If you have symptoms or concerns, please see a doctor.
