• visible variant TB0413-UKUD^^A Side Effect in Aubergine (dark purple) Ballistic with Ultraviolet (purple with white grid) 200 Halcyon interior.
  • visible variant TB0413-UKUD TB0413-UK1D TB0413-UK7D TB0413-UKGD TB0413-UKLJ TB0413-UKLD TB0413-UKND TB0413-UKGL TB0413-UKYD TB0413-UK9D TB0413-UKDL^^A Side Effect in Aubergine (dark purple) Ballistic.
  • lifestyle visible^^Person unzipping Side Effect.
  • visible lifestyle^^ Person opening the main pocket of their Side Effect while wearing it as a hip bag
  • lifestyle visible^^ Person pulling a Mystery Organizer Pouch out of Side Effect
  • lifestyle visible^^Two people holding hands wearing Side Effect and Side Kick.
  • lifestyle visible^^Person wearing the Side Effect as a hip bag
  • lifestyle visible^^Person wearing Side Effect on back of person wearing Side Kick.
  • lifestyle visible^^Two people holding hands wearing Side effect and Side Kick.
  • lifestyle visible^^Two people sightseeing wearing Side Effect and Side Kick.

Core Colors

Available Core Color options

Limited Edition Colors

Available Seasonal Color options
Exterior Color: Aubergine
Interior Color: Ultraviolet
Material: Ballistic
Material: 200 Halcyon

Perfect Pairings

visible variant TB0510
Key Strap Add a key strap to attach your bag to a larger bag, or to clip other items onto your bag. $8
visible variant TB0513-BA^^An 8-inch Black Key Strap with a snaphook at either end.
Choose Style

Color : Black Webbing

Available Color options
Lifetime Guarantee, 60-Day Returns, and Fast Shipping

The Side Effect is a compact, versatile crossbody bag that keeps your essentials organized and close at hand. It’s the smallest of our crossbody trio – more compact than the Side Kick and Side Hustle, making it ideal for those who carry just the essentials.

$70

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Side Effect Key Features

Interior Storage, Simplified

An open main compartment with two open-top pockets keeps things neat without bulking it up.

Carry It Your Way

Switch between a crossbody, shoulder, or organizer pouch in a larger bag. Travel how you want, without overthinking it.

Clip It and Forget It

Five O-rings to tether your essentials. Keep the important things where you need them—no digging required.

Everything in Its Place

One front zippered exterior pocket keeps your grab-and-go essentials within arm’s reach.

Interior Storage, Simplified

An open main compartment with two open-top pockets keeps things neat without bulking it up.

Carry It Your Way

Switch between a crossbody, shoulder, or organizer pouch in a larger bag. Travel how you want, without overthinking it.

Clip It and Forget It

Five O-rings to tether your essentials. Keep the important things where you need them—no digging required.

Everything in Its Place

One front zippered exterior pocket keeps your grab-and-go essentials within arm’s reach.

Lifetime Guarantee

We stand behind our work. If your bag ever develops a defect in materials or workmanship, we'll make it right so you can carry it with confidence for years to come.

60-Day Returns

Try your bag at home and make sure you like the fit, look, and organization. If it's not quite right, you can return it within 60 days for a refund or exchange.

Fast Shipping

We get your bag to you fast so you can start using it right away. Most in-stock orders ship the same or next business day.

This is a carousel with slides that contain product key features. Use Next and Previous buttons to navigate.

Side Effect Key Features

Interior Storage, Simplified

An open main compartment with two open-top pockets keeps things neat without bulking it up.

Carry It Your Way

Switch between a crossbody, shoulder, or organizer pouch in a larger bag. Travel how you want, without overthinking it.

Clip It and Forget It

Five O-rings to tether your essentials. Keep the important things where you need them—no digging required.

Everything in Its Place

One front zippered exterior pocket keeps your grab-and-go essentials within arm’s reach.

Interior Storage, Simplified

An open main compartment with two open-top pockets keeps things neat without bulking it up.

Carry It Your Way

Switch between a crossbody, shoulder, or organizer pouch in a larger bag. Travel how you want, without overthinking it.

Clip It and Forget It

Five O-rings to tether your essentials. Keep the important things where you need them—no digging required.

Everything in Its Place

One front zippered exterior pocket keeps your grab-and-go essentials within arm’s reach.

Reviews

4.9
Rated 4.9 out of 5 stars
Based on 439 reviews
Total 5 star reviews: 417 Total 4 star reviews: 19 Total 3 star reviews: 2 Total 2 star reviews: 1 Total 1 star reviews: 0
4.9
Rated 4.9 out of 5 stars
Based on 439 reviews
Reviews Summary
Customers say this crossbody bag is the perfect size for daily essentials like phone, wallet, keys, and sunglasses. Many reviews mention its versatility, working well as a crossbody, hip bag, or travel organizer. Users appreciate the quality construction, smooth zippers, and interior organization pockets. The Spectron fabric receives frequent praise for being lightweight yet durable. Common feedback includes satisfaction with the bag's capacity despite its compact size. Some customers prefer upgrading to a wider 1-inch strap for comfort. Overall, reviewers consistently describe it as their ideal everyday carry bag.
Slide 1 selected
439 reviews
  • MH
    Melanie H.
    Verified Buyer
    Reviewing
    Side Effect
    I recommend this product
    Bought For Myself
    Product Standouts Thoughtful Design, Compact, Versatile, Easily Adjustable, Comfortable
    Rated 5 out of 5 stars
    3 years ago
    Perfect everyday bag!

    Great size for a small purse or everyday bag. Well thought-out organizational pockets. Light weight with a comfortable strap that's easily adjustable and doesn't tangle or slip. It's also a perfect in-flight bag to hang from the airplane seatback (demonstrated in the first photo below, using TB swivel carabiners). A really versatile bag that holds more than it appears. One of my most-used and favorite TB bags!

    Shown below:

    -How it would hang from an airplane seatback

    -Interior pockets

    -Next 3 photos: inside a TB Daylight Briefcase, Co-Pilot (exterior pocket), and Truck (exterior pocket)

  • M
    Mélanie
    Verified Buyer
    Reviewing
    Side Effect
    I recommend this product
    Rated 5 out of 5 stars
    5 years ago
    The perfect hand bag

    I bought my first Side Effect in my very first TB order about 8 years ago. It has been my hand bag ever since. It holds key, wallet, phone, driving licence, tissues, lipstick, small change, sanitizer, and it's not even full. When black halcyon came out i bought another one, as i found halcyon can fit even more, and it's also lighter, and i prefer the look. I love also that the side effect fits in the bottom pocket of the Synapse 25 or in a side pocket of my aeronaut 30 when i'm flying with one-bag policy only. In black halcyon it fits with every outfit i wear. I also bought later on a side kick to see if it would be a better hand bag - but far too big for me :) if you are a minimalist lady like me (at least when it comes to hand bag content) you will love it! I recommend 100%

  • BL
    Bradford L.
    Verified Buyer
    Reviewing
    Side Effect
    I recommend this product
    Bought For Gift
    Product Standouts Thoughtful Design, Sewn in USA, Great Gift, High Quality Finishings, High Quality Craftsmanship
    Rated 5 out of 5 stars
    3 years ago
    Awesome "kit" bag

    I bought this to store a portable heating pad and accompanying accessories and it happens to be the perfect size for everything. I'm a huge sucker for the O -rings inside, and as with any bag I've had from these guys, the storage compartments just make sense. Far too often those small compartments just get in the way but with these bags you truly are getting the most legit bag experience possible. Treat yo self. And hey Tom and Friends! I really dig the saturated colors like alphaviolet and Viridian and would love to see more of that in the future. I also really love the Moab Halcyon, its under represented in the organizer bag category!

    All in all, my favorite thing about the bag is knowing that the people who made it get breaks and seem to be treated pretty damn well. I'm definitely not made of money but bags are something you want to buy nice, not twice. And while these are at the higher end of whats in my range, they seem to be worth every penny and the company from what I can tell has a business model that others should learn a lesson from.

    -guy who sewed a bunch of band patches on a vest and fancies himself to know a thing or two about good stitching.

    *If anyone happens to be wondering, it is slightly too small for a Nintendo Switch!

  • JL Profile picture for Jessica L.facebook logo
    Jessica L.
    Verified Buyer
    Reviewing
    Side Effect
    I recommend this product
    Bought For Myself
    Product Standouts Thoughtful Design, Compact, Versatile, Comfortable, Sewn in USA
    Rated 5 out of 5 stars
    3 years ago
    Perfect- inside other bags, or as it's own thing!

    I currently use a cubelet + super mini ghost whale + Nik's wallet inside a side effect as an every day purse like object carried cross body. I can carry my Pixel 6 phone, kindle paperwhite, headphones, sanitizer, extra K-95 mask, and keys. When I went to a recent work conference, it was easy to slip off the straps, and stash my side effect inside an icon. I could also take out the cubelet and carry it with a wrist strap. I am excited to use the side effect during the school year inside a teacher bag/backpack in this fashion, so that I can just take it out and put the strap on for the weekend/after school.

  • SS
    Sarah S.
    Verified Buyer
    Reviewing
    Side Effect
    I recommend this product
    Bought For Myself
    Product Standouts Comfortable, High Quality Craftsmanship, Versatile
    Rated 5 out of 5 stars
    3 years ago
    Almost Perfect

    The size of this bag is perfect for daily carry for an average day. The materials are quality and the organizational pockets on the interior are clutch. I do wish however that there were pockets inside of the front zip compartment. I like being able to add in some easy access items to the front of bags but like to keep them stored separately so I can differentiate things like keys and medicine easily. Also would love it if there were a pen/pencil pocket in the main compartment. I love that it can be worn multiple ways as well! But I do find the waist strap is too short to wear my bag across the chest which is disappointing but typical as I have a larger bust (~48 inches) but it fits perfectly as a waist bag and crossbody purse.

Everyday Carry, Everywhere

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