How do I use the Undu 'Original' Heat Pack? 

1- First Time, Soften: When your Original Heat Pack arrives, it will be stiff. Let it sit in a dish of hot water until it has softened.

2 - Heat it: The Original Heat Pack can now be rolled and fully heated in a mug with boiling water, in the microwave, or on the stove!

*If you ever see oil in the water, consider the Heat Pack broken and do not continue to use it. Send us an email at:

3 - Wear it: Carefully remove the Heat Pack. Always have a layer of fabric between you and the Heat Pack. The Keep It Brief is ideal! Place the Heat Pack on your lower abdomen or back to feel relief. Repeat for as many times as you’d like! 

4 -Storing: When you’re finished with the Original Heat Pack, roll it up while it’s still soft and place it in the cloth bag provided. This will remove Step 1 next time you use it! 

As always, take care when using hot water!

Check out this blog post from one of our Co-Founders for more info!

How long does the heat last? 

After each melt The Original Heat Pack provides heat for 25-30 minutes (but stays warm to the touch longer). Reheat quickly for relief that helps you all day. 

What size underwear am I? 

Our sizing is simple! We’ve decided to directly reflect your waist dimensions in the sizing of our underwear. If you have a 24”-25” waist, select size 24-25. More questions? See the chart below!


[Back to Briefs!]

What about returns? 

We want you to feel safe, comfortable, and relieved!
If that’s not the case, reach out to us at and we’ll figure it out!

Do you sell outside of Canada? 

Right now we are made entirely in Ontario and are proud to be launching exclusively in Canada!  We’re excited to grow and sell to more parts of the world. Join our mailing list to stay up-to-date on our progress!

What can I expect after I place an order? 

First of all, thank you for supporting our new business! 

We make the Original Heat Pack by hand in our Haliburton workshop. We will work to get you your order as soon as possible, but delivery times may vary as we learn to scale our production. 

Feel free to send us an email with any questions!

Why heat?

Heat therapy has been used since 500 B.C. Applying heat to the outside of the body is a noninvasive way to treat muscle aches and pains… like menstrual cramps! The heat loosens tissues and stimulates blood flow to the area, promoting healing, decreasing pain, and relaxing muscles. 

We conducted a survey and learned that 61% of people who experience menstrual pain use heat to relieve their symptoms. Here’s a helpful article where you can learn more! 

It’s always a good idea to consult with your doctor if you have any concerns.


We're proud to offer free shipping in Canada! 


We still make our heat packs in small batches from our workshop in Haliburton. We'll always do our best to ship immediately, but sometimes require 1-2 weeks to ship depending on inventory.