What Are the Signs of Low Testosterone in Men?

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Dr. James D. Fontaine

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4/15/2026

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Low testosterone is more common than you might think, but the signs are often mistaken for stress or normal signs of aging. Low T symptoms may include low energy, reduced muscle mass, increased body fat, mood changes, brain fog, low libido, erectile dysfunction (ED), or poor sleep. 

 The good news? Treatments like hormone optimization can make a big difference and improve your quality of life. 

At Fontaine MD Aesthetics and Anti-Aging Medicine in San Diego, CA, Dr. James D. Fontaine specializes in helping men identify the root cause of their issues and create a treatment plan that delivers results. Call today to schedule testosterone therapy and start feeling like yourself again. 

What causes low testosterone? 

So, what causes low testosterone? For many men, the primary cause is simply age. Testosterone levels are highest in early adulthood and then gradually decrease over time. 

However, age isn't the only factor. Testosterone levels can also drop more significantly due to chronic stress, certain medications, and underlying health conditions like thyroid disorders. Pinpointing what causes low testosterone in your specific situation is the first step toward effective treatment. For many, solutions like testosterone therapy can help restore balance and improve overall well-being. 

Low T symptoms to watch for 

Low T can show up in a variety of ways. Here are some common signs that your testosterone levels might be out of balance:  

  • Fatigue and low energy: Feeling consistently drained regardless of how much you sleep 
  • Reduced muscle mass: Difficulty building or maintaining muscle, even with regular exercise 
  • Increased body fat: Usually around the abdomen, without any major changes in diet 
  • Mood changes: Irritability, depression, or a general feeling of anxiety 
  • Brain fog: Trouble concentrating or feeling mentally sharp 
  • Low libido: A noticeable and persistent drop in sex drive 
  • Symptoms of erectile dysfunction: Difficulty achieving or maintaining an erection 
  • Poor sleep: Insomnia or disrupted sleep patterns that leave you feeling unrested 

If one or more of these issues sound familiar, including mood changes or symptoms of erectile dysfunction, getting your levels tested in San Diego, CA is a straightforward way to find out whether low testosterone is the cause. 

How we treat low testosterone 

Hormone optimization at Fontaine MD Aesthetics and Anti-Aging Medicine starts with a thorough evaluation of your blood work and health history. From there, we can recommend a hormone delivery method that fits your lifestyle and goals. Options include:  

  • Hormone pellets: These are tiny implants placed just under the skin. Hormone pellets release a steady, gradual dose of testosterone over several months. 
  • Injections: This involves injecting testosterone directly into a muscle. Injections are typically scheduled on a regular basis. 
  • Topical gels and creams: If you prefer a noninvasive option, you can apply a gel or cream to your skin daily. It’s a convenient way to get a consistent dose of hormones. 
  • Patches: Another easy-to-use option. You simply wear a patch on your skin and change it regularly to achieve a steady release of testosterone throughout the day. 

Most men begin noticing improvements within the first few weeks of starting testosterone therapy, with more meaningful changes developing over the following months. 

Start feeling like yourself again 

Low T symptoms are not something you have to live with when effective treatment exists. At Fontaine MD Aesthetics and Anti-Aging Medicine in San Diego, CA, Dr. James D. Fontaine brings a personalized, evidence-based approach to hormone optimization for each patient. 

Whether you have questions about hormone pellets or want to understand more about the symptoms of erectile dysfunction, we can help. Call today to schedule your consultation.

When I came to Dr. Fontaine several years ago, I was going into early menopause and experiencing so many symptoms. Hot flashes, fatigue, pain, brain fog, and depression that were being dismissed by my regular doctors. Dr. Fontaine was truly a godsend. He listened, took my concerns seriously, and helped me create a plan that worked for my body. Over time, we adjusted my medication, and I now feel 100% better. I’m so grateful for his care and support!

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Louise initially treated me with Botox at an MD clinic I had been using for years. I was so pleased with my results, when she moved to Fontaine MD I followed her even though it was much farther away. Recently, I decided to also get fillers and expressed to her my desire for a very natural and youthful look, and she nailed it! She is a licensed RN with an Art degree therefore she really understands the anatomy and symmetry of the face. She is welcoming, professional, never rushes and very skilled at injecting both Botox and fillers, I highly recommend Louise!I also highly recommend Fontaine MD, great Doctor, and staff in a lovely, serene setting. They were instrumental in aiding me in a 20+ lb weight loss (so easy) and I could not be more grateful. I feel and look so much better and have maintained my new weight. That is not easy for many 60-year-old females.

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Louise is absolutely wonderful to work with! I have seen her for both an IPL facial and Botox (my very first time!). She took the time to answer my questions, address my concerns, and put my mind at ease. I could sense that I was in the hands of someone who was going to take care of me. Louise cares about her clients and their desired outcomes. I have done IPL facials in the past with other providers and the procedures felt very harsh on my skin. With Louise, my skin was not red, bumpy, or painful after and my sunspots were treated effectively! I also trusted Louise with my first Botox experience. Louise made me feel both comfortable and excited about the natural but effective results I was hoping to have! I am thankful I found Louise and will be a returning client!

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Louise listened to my skin concerns, made recommendations and completed Botox and filler procedures that that made an amazing difference!

C.T. Google

Before seeing Dr. Fontaine, I had no idea I could feel better. I just assumed that as I got older, low energy, hormonal struggles, and general decline were just part of life—something I had to accept. Looking back, I realize how much I had normalized feeling exhausted, unmotivated, and off-balance. My energy had dipped, my sleep was inconsistent, and no matter what I did, things like weight gain and mood swings seemed unavoidable. I wasn’t in crisis—I just wasn’t thriving. Dr. Fontaine completely changed that. From the first appointment, he took the time to listen, evaluate my symptoms, and explain what was really happening in my body. Seeing my lab results was an eye-opener—I finally had real data that explained why I felt the way I did. Within a couple of months of starting treatment, I started feeling like myself again. My energy improved, my focus sharpened, and I finally started sleeping through the night. Over time, the changes were undeniable—I was stronger, my mood was steady, and I didn’t feel like I was constantly fighting against my own body. Dr. Fontaine has been with me every step of the way, adjusting my treatment as needed and making sure I feel my best. He’s thorough, knowledgeable, and truly invested in his patients' well-being. I never feel rushed in my appointments, and he always takes the time to answer my questions. I didn’t realize how much I was missing out on until I started feeling this good again. Now, I feel like I’ve regained the energy, confidence, and vitality I thought were long gone. I’m beyond grateful to Dr. Fontaine for helping me.

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