Short answer: In the label's 90-day placebo-controlled Testim trial, side effects were uncommon: application site reactions were 2% on 50 mg and 4% on 100 mg vs 3% on placebo, raised hematocrit or hemoglobin 1% and 2% vs 0%, and higher blood pressure, headache and taste changes about 1% each. In a 16-week study, blood pressure rose an average 2.7/1.1 mm Hg. A boxed warning covers testosterone passing to children through skin contact.
What Testim is approved for: Testim is approved as testosterone replacement in adult males with low or absent natural testosterone due to primary hypogonadism (testicular failure) or hypogonadotropic hypogonadism (a pituitary or hypothalamus cause). The label says safety and efficacy have not been established in men with "age-related" (late-onset) hypogonadism or in males under 18 (section 1).
Source
TESTIM (testosterone gel) for topical use, CIII, prescribing information, Medication Guide and Instructions for Use. Endo USA. DailyMed, version published March 5, 2026. DailyMed setid 9f2aae1f-898d-4955-be31-678e0cf85395
WARNING: SECONDARY EXPOSURE TO TESTOSTERONE
Virilization (male-type changes) has been reported in children who were exposed to testosterone gel through someone else. Children should avoid contact with unwashed or unclothed skin where a man has applied testosterone gel. The label says healthcare providers should advise patients to strictly follow the instructions for use.
These are the label's own numbers from the Adverse Reactions section. Where the label compares with placebo (a dummy treatment), both columns are shown, so you can see how much more often a reaction happened on Testim.
| Event | TESTIM 50 mg (n=103) | TESTIM 100 mg (n=149) | Placebo (n=99) |
|---|---|---|---|
| Application Site Reactions | 2% | 4% | 3% |
| Blood Pressure Increased | 1% | 1% | 0% |
| Gynecomastia | 1% | 0% | 0% |
| Headache | 1% | 1% | 0% |
| Hematocrit / hemoglobin Increased | 1% | 2% | 0% |
| Hot Flushes | 1% | 0% | 0% |
| Insomnia | 1% | 0% | 0% |
| Mood Swings | 1% | 0% | 0% |
| Smell Disorder | 1% | 0% | 0% |
| Spontaneous Penile Erection | 1% | 0% | 0% |
| Taste Disorder | 1% | 1% | 0% |
205 men on Testim 50 mg or 100 mg and 99 on placebo gel for up to 90 days. Men could be counted in both Testim columns if they used both doses at different times.
In this trial, 6 men stopped because of side effects, including depression with suicidal thoughts, urinary tract infection, mood swings and high blood pressure. None stopped because of a skin reaction.
In the US and European Phase 3 trials combined, on 100 mg, 2.3% had a notable rise in hemoglobin (19 g/dL or more) and 2.8% in hematocrit (58% or more), vs 1.0% and 1.5% on placebo. On 50 mg, rates were similar to placebo.
Blood pressure: in 113 men with 24-hour readings, systolic rose by an average of 2.7 mm Hg and diastolic by 1.1 mm Hg after 16 weeks. In men already on blood pressure medicine the rise was 1.9/0.3 mm Hg. 6 of 225 men (2.7%) had hypertension reported as a side effect.
In the TRAVERSE heart-safety study of 5198 men using a topical testosterone gel, major heart events were 7.0% vs 7.3% on placebo. Irregular heartbeats needing treatment (5.2% vs 3.3%), atrial fibrillation (3.5% vs 2.4%), acute kidney injury (2.3% vs 1.5%) and bone fracture (3.5% vs 2.5%) were more common on the gel.
Transfer to partners: after 100 mg on the man's upper arms and shoulders and 15 minutes of skin-to-skin rubbing 4 hours later, women's testosterone rose about 4 times from baseline. When the man wore a long-sleeved T-shirt, transfer was prevented.
The Warnings and Precautions part of the label lists these. Each line gives the label's heading and what it means in plain words.
Who should not use it. Men with breast cancer or known or suspected prostate cancer, and women who are pregnant, since testosterone can cause male-type changes in a female fetus.
Testosterone passing to others. Children exposed to testosterone gel have shown enlarged penis or clitoris, pubic hair, increased erections and libido, aggressive behavior and advanced bone age. Most cases improved once exposure stopped, but a few did not fully return to normal. Testim is stopped until the cause of any such signs is found.
Polycythemia (high red blood cells). Hematocrit is checked before starting, again 3 to 6 months after starting, and then once a year. If it is high, therapy is stopped until it comes down.
Blood clots. Deep vein thrombosis and pulmonary embolism have been reported with testosterone products. In TRAVERSE, clots occurred in 1.7% on testosterone gel vs 1.2% on placebo. If a clot is suspected, Testim is stopped.
Enlarged prostate and prostate cancer. Men with BPH may see symptoms worsen, and androgens may raise prostate cancer risk. The label says to check for prostate cancer before and during treatment.
Blood pressure increases. Testim can raise blood pressure, which can raise heart risk over time. Blood pressure is checked periodically, and it is not recommended with uncontrolled high blood pressure.
Abuse and testosterone level checks. Testosterone has been abused at higher-than-approved doses, often with other anabolic steroids, which can cause serious heart and mental health problems. If abuse is suspected, serum testosterone is checked.
Women and sperm production. Testim is not indicated for women. Large doses of testosterone can suppress sperm production and lower sperm count.
Liver and fluid retention. Testim is not known to cause the liver problems linked to high-dose oral androgens, but patients are told to report signs such as jaundice, and Testim is stopped while the cause is checked. Androgens can cause salt and water retention, which can be serious with heart, kidney or liver disease.
Breasts, sleep apnea and lipids. Breast enlargement may develop and persist. Testosterone may worsen sleep apnea, especially with obesity or chronic lung disease. Blood fats can change, so lipids are checked periodically.
Calcium and thyroid lab values. In cancer patients at risk of high calcium, calcium is checked regularly. Androgens can lower thyroxine-binding globulin and total T4, but free thyroid hormone stays the same.
Flammability. The gel is alcohol-based and flammable, so fire, flames and smoking are avoided until it has dried.
From the Medication Guide that comes with Testim:
Dose Track has a side-effect log. Each entry records the symptom, a severity (none, mild, moderate, severe or life-threatening), the date and an optional note, and can be tied to a specific dose or logged on its own. The history screen shows what you logged over time, which makes it easier to tell your prescriber when a reaction started and whether it is easing. The app records what you enter; it does not judge whether a symptom is serious. For anything on the label's call-your-doctor list, call your doctor.
This page is what the FDA label says, in plain words. It is not medical advice. Follow your prescriber, and ask them or your pharmacist about anything here.