Many people with breast cancer undergo axillary (armpit) lymph node removal as part of their treatment. Following this surgery, some MyBCTeam members have noticed new and unusual changes in their underarms. “One armpit is stinky, and the other one isn’t even wet!” one MyBCTeam member said.

This article explains how breast cancer treatment may change the way you sweat, explores how MyBCTeam members describe changes in their armpits, and offers practical tips for managing excessive sweating.

Members’ Descriptions of Changes After Lymph Node Dissection

Noticing changes in your body after treatment can be confusing. “I had an odd odor on that side for a couple of months and even asked my surgeon about it,” one MyBCTeam member said about the armpit that had surgery. “After a while (maybe three months), it went away and the glands worked normally.”

“I have noticed that I don’t sweat from my armpit on the affected side,” one member said. “My sweating is localized to the side where I didn’t get surgery.”

Members also describe changes in hair growth. “I had five lymph nodes removed from my right armpit, and now I haven’t had the need for deodorant or shaving,” another member shared. “I just can’t forget to shave my hairy left armpit — now, that would be embarrassing.”

Based on these and other MyBCTeam members’ experiences, one-sided sweating, odor, or changes in hair growth after lymph node removal aren’t uncommon.

Reasons for 1-Sided Sweat Changes

Whether you’re experiencing more or less sweating in one armpit, there may be several reasons for these changes.

Lymph Node Dissection

Common side effects after a lymph node removal include swelling, stiffness, and scarring. Many people who have this procedure also report less sweating or no sweating on one side.

In one study of 65 people who underwent lymph node removal, 29 reported reduced underarm sweating in the affected armpit.

The reasons for this symptom aren’t well understood. It may be caused by damage to the nerves in the underarm that signal the sweat glands to produce sweat.

Other Breast Cancer Treatment

Nonsurgical breast cancer treatments, including radiation therapy, chemotherapy, and hormone treatment, can also change the way you sweat.

People who receive these treatments may experience hot flashes and night sweats, which can increase sweating in one or both armpits. If you’ve also had lymph node removal on one side, changes in sweating and odor may be even more noticeable after treatment.

MyBCTeam members have shared that their underarm odor changed after radiation or chemotherapy. “It didn’t smell foul, it just smelled weird. Happily, though, it did go away within a few months of stopping chemo,” one member wrote.

Another said, “I had the same problem. I would put so much deodorant on trying to smell good, it would be crumbling down my side. It goes away after radiation.”

Some types of breast cancer surgery may also change underarm sweating and odor. “I had a double mastectomy, and since then I haven’t had any underarm odor,” one MyBCTeam member wrote.

Other Causes

Other conditions can also cause one-sided sweating. For example, if you suddenly start sweating on just one side of your body without another clear explanation, you may have unilateral hyperhidrosis, also known as asymmetric hyperhidrosis. This condition can happen when there’s a problem with the autonomic nervous system, which controls automatic body functions you don’t have to think about, such as sweating and breathing.

Many conditions can affect the autonomic nervous system, so it’s important to talk with your doctor about possible underlying causes. See your doctor right away if severe one-sided sweating happens along with dizziness, nausea, clammy skin, or seizures.

Managing 1-Sided Sweat Changes

What can you do about one-sided underarm changes? Many MyBCTeam members have chosen to look on the bright side: “I am kind of happy with not having to shave or use antiperspirant under the affected arm,” one shared.

Sweating, odors, and hair growth are all normal functions of the underarms. Breast cancer treatment may increase, reduce, or stop sweating on one side, while the other underarm may continue to function as it did before.

Options for preventing or managing excess sweating include:

• Antiperspirants and deodorants — There is no scientific evidence that these products increase the risk of breast cancer. If you’re experiencing excess sweating or odor on one side, they are generally considered safe to use.
• Prescription gels — Sofpironium is a prescription gel that helps reduce sweating. It’s applied to the underarms once daily and works by blocking signals that activate the sweat glands.
• Prescription wipes — Glycopyrronium tosylate prescription wipes can help reduce the amount of sweat your armpit produces.
• Dermatology procedures — Procedures such as botulinum toxin injections can help reduce underarm sweating. In some cases, surgery may also be an option.

Talk to your doctor if excessive armpit sweating is affecting your quality of life.

Speak With Your Doctor

Experiencing unexpected symptoms after lymph node dissection or other breast cancer treatments is common. Your symptoms may be different from someone else’s, which can make it hard to know what to expect after treatment. “Nice if someone would have told us, huh?” one member said.

Although it may feel embarrassing to bring up this symptom, many people have experienced similar changes after treatment. If one-sided sweating is bothering you, or if you also have symptoms such as swelling or pain, talk with your oncologist or breast surgeon.

Join the Conversation

On MyBCTeam, people share their experiences with breast cancer, get advice, and find support from others who understand.

Have you experienced changes in sweating after lymph node removal? How did you manage your symptoms? Let others know in the comments below.