If you’ve been diagnosed with hormone receptor–positive breast cancer, there’s a good chance you’ve heard the term aromatase inhibitor (AI). These powerful medications are one of the cornerstones of modern breast cancer treatment — helping reduce recurrence and improve long-term survival for millions of women worldwide.
But like many things in breast cancer care, they come with their own set of questions, side effects, and adjustment periods.
As someone who takes letrozole daily and is tolerating it well, I know that understanding how these drugs work — and what to expect — makes a big difference in how you feel both physically and emotionally.
Let’s break it down together.
What Are Aromatase Inhibitors?
Aromatase inhibitors (AIs) are medications that block the production of estrogen — a hormone that can fuel the growth of certain types of breast cancer.
They work by inhibiting an enzyme called aromatase, which converts androgens (produced in the adrenal glands and fat tissue) into estrogen.
By reducing estrogen levels in the body, AIs “starve” hormone receptor–positive cancer cells and reduce the risk of recurrence after primary treatment.
The three main AIs prescribed today are:
- Letrozole (Femara)
- Anastrozole (Arimidex)
- Exemestane (Aromasin)
They’re typically taken once daily for 5 to 10 years, depending on your cancer type, stage, and recurrence risk.
Learn more about AIs from the American Cancer Society.
How Aromatase Inhibitors Differ From Tamoxifen
Tamoxifen — another hormone therapy — works differently. Instead of blocking estrogen production, tamoxifen blocks estrogen receptors on cancer cells, preventing the hormone from attaching and stimulating growth.
Tamoxifen is often prescribed for premenopausal women, while AIs are most effective in postmenopausal women or in women who’ve had ovarian suppression as part of treatment.
Some women take tamoxifen first, then switch to an AI after menopause or a few years into therapy.
Common Side Effects — and How to Manage Them
Like any medication that changes hormone levels, AIs can bring side effects. Some are mild and manageable; others require more active intervention.
Here’s what many women experience — along with strategies that can help.
1. Joint and Muscle Pain
The most common side effect. The pain may feel like stiffness in your hands, hips, knees, or lower back, especially in the morning or after sitting.
Tips:
- Stay active — gentle movement like yoga, walking, and stretching can help.
- Consider strength training to support your joints.
- Discuss over-the-counter pain relievers or omega-3 supplements with your doctor.
- Some women find relief with acupuncture or physical therapy.
👉 Read more: Exercise During and After Cancer Treatment
2. Bone Loss (Osteopenia or Osteoporosis)
Because estrogen helps protect bone density, lowering it can lead to thinning bones over time.
Tips:
- Ask for a DEXA scan every 1–2 years.
- Take calcium and vitamin D as recommended by your oncologist.
- Engage in weight-bearing exercises like walking or light weights.
- Your doctor may recommend bone-strengthening medications such as bisphosphonates or denosumab.
3. Hot Flashes and Night Sweats
These can appear similar to natural menopause symptoms.
Tips:
- Keep your environment cool and wear breathable fabrics.
- Avoid alcohol, caffeine, and spicy foods.
- Try deep breathing or mindfulness exercises before bed.
- Some women benefit from non-hormonal medications prescribed for symptom relief.
👉 Read: Managing Menopause After Breast Cancer
👉 Or explore: Coping With Hot Flashes Without Hormones
4. Fatigue and Low Energy
AI-related fatigue is real — and it’s not “just in your head.”
Tips:
- Prioritize rest and consistent sleep.
- Move daily — even 20 minutes of walking helps.
- Eat for steady energy: protein, fiber, and healthy fats.
- Ask your doctor to check for anemia or thyroid issues if fatigue persists.
5. Mood Changes or Brain Fog
Lower estrogen can affect neurotransmitters linked to mood and memory.
Tips:
- Practice mindfulness, yoga, or journaling.
- Talk to your care team about CBT or medication support if needed.
- Stay connected — community matters.
- Keep your brain active with reading or puzzles.
Personal Note: My Experience on Letrozole
I’ve been taking letrozole as part of my ongoing treatment — and so far, I’m tolerating it well.
Some mornings I feel stiffness or mild fatigue, but movement and mindfulness make a big difference. Most importantly, I remind myself why I’m taking it: to protect my health, reduce recurrence risk, and keep living the full, active life I’ve rebuilt.
If you’re just starting on an AI, give yourself time. Your body will adapt — and support is available every step of the way.
When to Call Your Doctor
Contact your healthcare provider if you experience:
- Severe joint or bone pain
- Unmanageable fatigue
- Sudden mood changes
- Any new or concerning symptoms
Your oncologist may adjust your dose or switch medications. Sometimes small changes — even the time of day you take your pill — can help.
Living Well on Aromatase Inhibitors
While aromatase inhibitors can bring challenges, they are also a powerful safeguard — helping you move forward with confidence and protection.
Pair your treatment with self-care, movement, and emotional support for a whole-body approach to survivorship.
At AskEllyn.ai, we believe in empowering women to understand their treatments, listen to their bodies, and live fully — during and after cancer.
Explore more guides and survivor stories:
- 💗 Managing Menopause After Breast Cancer
- 🌿 Coping With Hot Flashes Without Hormones
- 🦋 The Ultimate Guide to the Butterfly Effect
Disclaimer: AskEllyn.ai provides information for educational purposes only and does not replace medical advice. Always consult your healthcare provider before starting, stopping, or changing any treatment.
