I knew to expect side effects with chemo …
but I had no idea I’d struggle with the estrogen blocker.

I thought this was going to be the easy part!

For many patients, treatment with hormone therapy feels like somewhat of an epilogue – the treatment after The Treatments, a top-off to prevent cancer from adding a new chapter to the story. Epilogues aren’t supposed to include dramatic twists, so when side effects show up at this point, patients can feel blindsided.

If you’re experiencing side effects from hormone therapy cancer treatment (e.g., aromatase inhibitors, tamoxifen), you’re not alone. Many people do, and many stop treatment because of side effects.

You shouldn’t have to weigh the value of an important preventive measure against the side effects.

And there are specialists who may be able to help you.

The Connection to Other Specialties

Some cancers get their fuel from hormones in the body. Hormone therapy cancer treatments — also called endocrine therapy, hormone blocker therapy, or anti-hormone therapy — work by altering our hormones to deprive cancer cells of the fuel they need.

Along with depriving cancer cells, these treatments also shake up our immune system. Our sex hormones — estrogen, progesterone, and testosterone — play an active role in regulating our immune system; they’re involved in the development of our immune cells, as well as their activity and their signaling. 

When hormone therapy disrupts our hormones, it disrupts our immune system, which can cause our immune cells to become overactive and begin attacking the body’s own tissues. This is where side effects come from.

Many of the side effects of hormone therapy cancer treatment closely resemble the types of symptoms that we see in autoimmune conditions.

Autoimmune conditions (e.g., rheumatoid arthritis, lupus) occur when the immune system mistakenly launches an attack against healthy tissue – similar to the attack on our body’s tissues that can occur in the wake of hormone therapy cancer treatments. Because there’s a similar process at play, the resulting side effects look similar, as well. 

Let’s look at the similarities between side effects and autoimmune symptoms.

If you are experiencing one of these hormone therapy side effects, it does not mean that you have the condition in the righthand column – but it does offer a clue to possible treatment options for your side effects. 

Doctors have found that, in many cases, drugs that ease the symptoms of autoimmune conditions often ease the side effects of the temporary “autoimmune” state created by your cancer treatment. 

To explore the possibility that drugs used for autoimmune conditions might help your side effects, you’ll need to see a specialist who treats the autoimmune condition(s) that correlate to your side effects.

Rheumatologists, neurologists and neuropsychologists, cardiologists, endocrinologists, mental health professionals, and physical medicine and rehabilitation specialists each have deep expertise in the kinds of inflammation that your hormone therapy side effects can cause. Involving the appropriate specialists, who know autoimmune treatments inside and out, can mean the difference between side effects being livable or life-altering.

Next Step: Talking to Your Cancer Team

Every patient’s relationship with their cancer team is different – some patients feel completely at ease asking to see a specialist; others feel anxious and unsure how to go about it. Below are some thoughts to keep in mind, as well as some tips for the conversation with your oncologist. 

We are all still learning. Many oncologists are not yet aware of the connection between cancer care and autoimmune condition care, which isn’t a failure on their part; this is relatively new information in a rapidly advancing field, and it simply may not have reached them yet. In cases like this, patients may be ones bringing helpful information to the table. We’ve prepared a printable document with information and links that may help. 

It’s normal to feel anxious. Approaching your cancer team with information you found on the internet can be anxiety-inducing: What if they think I’m questioning their ability? What if they don’t listen to me? But when you’re undergoing cancer treatment, you can’t afford to let this discomfort stop you from speaking up. To ease anxiety, consider bringing a support person with you to the conversation and come prepared with information to share (see above bullet).

The squeaky wheel … If your doctor doesn’t respond the way you’d hoped, do not be dissuaded. Talk to every person on your cancer team, and keep talking, until you get connected with a specialist. Advocating for yourself in this way may be far outside your comfort zone, and fatigue and pain may make it hard to find the energy, but you are worth the effort. For extra support, ask friends or family to help in your advocacy; online patient advocacy organizations may be of help, as well. 

Clear requests get the best results. Be prepared with clear information, questions, and requests for your doctor – and take notes during the conversation. Here are some suggestions:

• Name the specific symptom and the specific autoimmune condition it resembles. Be direct: “My joint pain and swelling look a lot like rheumatoid arthritis. Can we bring in a rheumatologist who has experience treating patients on hormone therapy?” Specificity helps your team act faster.
• Ask about multidisciplinary clinics that handle this type of thing. Many major cancer centers have dedicated irAE clinics (irAEs is another term for the side effects from hormone therapies). These centers involve specialists from different disciplines (rheumatologists, endocrinologists, etc.). Ask if this is available to you.
• Request a formal referral, not just advice. Ask your oncologist to make a formal referral — not just an informal suggestion. A referral ensures the specialist receives your medical records, understands your treatment context, and can follow up consistently.
• Ask about communication between your providers. “How will you and the specialist communicate about my care plan?” Ensuring your cancer team and any new specialists are in direct contact prevents conflicting advice and treatment gaps.

Preparing to See a Specialist

Before you see the specialist to discuss your side effects, it may be helpful to have some context about autoimmune conditions and how they’re treated. 

Specialists and Patients Work Together. The nature of autoimmune conditions necessitates a close, cooperative relationship between physician and patient. Because autoimmune conditions usually can’t be definitively diagnosed with a test or scan, physicians have to rely heavily on patients to give them the information they need to make a diagnosis. In these specialties, physicians are accustomed to working hand-in-hand with their patients to solve problems, so be prepared to play an active role in your care.

Management Requires Trial-And-Error. Because our immune system is individualized, a treatment plan that works for one patient may not work for another. So, be prepared for some trial-and-error. Again, good communication is essential for finding a treatment plan that is best for a patient.

The Better the Information, the Better the Care. The specialist will be making treatment decisions based on the information you provide, so keep a symptom log and bring it to every appointment. Document when symptoms appeared, how they have progressed, their severity on a 1–10 scale, and any patterns (time of day, activity level, foods). 

What You Can Do for Yourself Right Now

Because hormone therapy side effects look a lot like autoimmune condition symptoms, lifestyle tweaks that help people living with autoimmune conditions may help you, as well. 

These evidence-informed lifestyle strategies may help reduce inflammation, manage fatigue, and improve quality of life. Always discuss any new regimen with your care team before starting.

Movement and Physical Activity: Low-impact resistance and weight-bearing exercise reduces joint pain, builds bone density, and combats fatigue. Tai chi and yoga are specifically validated in autoimmune populations for pain management and mood. Consistency matters more than intensity: 20–30 minutes most days is more sustainable than sporadic intense sessions.

Anti-Inflammatory Diet: Mediterranean-style eating — emphasizing omega-3 fatty acids, colorful vegetables, olive oil, and limiting refined sugar and processed foods — reduces systemic inflammation and cardiovascular risk. Many autoimmune patients eliminate dietary triggers that worsen their individual symptoms.

Sleep Hygiene: Poor sleep amplifies pain sensitivity and immune dysregulation. Autoimmune patients prioritize consistent sleep schedules, cool sleeping environments (particularly helpful for night sweats and hot flashes), and addressing underlying sleep apnea, which is common in both populations.

Stress Management: Chronic stress elevates cortisol and pro-inflammatory cytokines, worsening nearly every symptom category. Mindfulness-based stress reduction (MBSR) has evidence in both autoimmune disease and cancer populations for reducing fatigue and improving mood. Even brief daily practice is beneficial.

Energy Pacing: A cornerstone of autoimmune fatigue management: planning activities to avoid boom-bust cycles, building in rest strategically, and learning individual energy thresholds. 

Heat and Cold Therapy: Warm water therapy (hydrotherapy) reduces joint stiffness, while cold packs manage acute inflammation and joint swelling. Both are widely used in rheumatology and directly applicable to hormone therapy-related arthralgia.

Peer Support and Community: Autoimmune communities have robust peer networks for practical coping strategies. Many online cancer support communities, and some autoimmune communities, openly welcome hormone therapy patients given symptom overlap. Shared experience reduces isolation and accelerates practical learning.