It is one of those questions that everyone wonders about but nobody wants to ask out loud: what exactly should you wear under your leggings? The answer is more nuanced than you might expect, and it genuinely affects your comfort, hygiene, and how your leggings look during your workout.
Some women swear by going commando. Others have specific underwear brands they will not work out without. And plenty of women are quietly wearing the wrong type of underwear under their leggings -- creating visible panty lines, dealing with chafing, or making hygiene mistakes they do not realize. Here is the complete, honest guide to what works, what does not, and what the actual medical experts say.
Should You Wear Underwear Under Leggings?
The short answer, according to OB-GYNs: both options are perfectly safe.
Dr. Mary Rosser, an OB-GYN at Columbia Doctors New York, puts it simply: "I tell people, 'Do whatever feels right for you.' Some people just feel they need to wear underwear; the thought of not doing so makes them uncomfortable." Dr. Raquel Dardik, an OB-GYN at NYU Langone, adds that your leggings should be "thick enough to prevent bacteria from gym equipment from transferring to your skin" if you choose to go without.
The choice comes down to your comfort, your leggings' construction, and the type of activity you are doing. Here is when each option makes the most sense:
When Going Commando Works
- Your leggings are high-quality, opaque, and have a built-in cotton or moisture-wicking gusset (the panel of fabric in the crotch area)
- You are doing a low-to-moderate impact activity where friction is minimal
- You wash your leggings after every single wear
- You find underwear uncomfortable, restrictive, or distracting during exercise
When You Should Wear Underwear
- Your leggings are thin, potentially sheer, or do not have a gusset
- You are doing high-friction activities (cycling, running, heavy lifting with wide stances)
- You are prone to yeast infections or UTIs and want an extra moisture-absorbing barrier
- You are sharing gym equipment and want maximum protection between your body and the fabric
- You plan to wear the leggings for extended periods before washing
The Best Types of Underwear for Leggings
Seamless Thongs
For zero visible panty lines (VPL), thongs are the most effective option. With minimal fabric, they create the smoothest finish under even the tightest leggings. However, there is a medical caveat: Dr. Michael Osmun, a family medicine physician, warns that thongs can "cause increased friction and irritation, leading to tiny cuts or microabrasions on the skin, which can result in bacterial infections." His recommendation: "It's likely safer to go without underwear than to wear a thong during exercise."
If you do wear thongs to the gym, choose seamless versions with flat, bonded edges rather than stitched seams. Match the rise of your thong to your leggings -- high-rise thongs under high-rise leggings, mid-rise under mid-rise -- so any seam lines align rather than showing at different levels.
Best for: Eliminating VPL, light gym sessions, yoga, pilates
Not ideal for: Running, HIIT, cycling, or women prone to infections
Seamless Bikini or Brazilian Cut
The middle ground between full coverage and no-line invisibility. Seamless bikinis and Brazilians offer more coverage than thongs while still staying relatively invisible under leggings. They are more comfortable for high-movement activities and reduce the infection risk associated with thongs.
Choose laser-cut or bonded edges -- these lie flat against the skin without the raised seam ridge that creates visible lines. Microfiber or nylon-spandex blends work best for this purpose.
Best for: General gym sessions, moderate-impact cardio, daily wear under leggings
Seamless Boyshorts
Boyshorts provide the most coverage and are excellent for preventing inner-thigh chafing during activities that generate friction -- cycling, running, and exercises with wide stances. Their longer leg line distributes pressure evenly and eliminates the rubbing that shorter cuts can cause.
The trade-off: boyshorts are the most likely to show lines under tight leggings, especially if the hem does not end at a natural body contour. Choose ultra-thin, seamless versions and avoid any with visible hems or decorative elements.
Best for: Cycling, running, long walks, high-friction activities, chafe-prone women
Performance/Athletic Underwear
Designed specifically for exercise, athletic underwear uses moisture-wicking fabrics, flat seams, and body-mapped construction to stay invisible and functional during workouts. Brands like Under Armour, Lululemon, and Gymshark make underwear specifically for wearing under leggings and athletic wear.
These are the most technically capable option -- purpose-built for the exact scenario of wearing under leggings during exercise. They cost more than regular underwear but are designed to solve every problem (VPL, moisture, friction, odor) in one piece.
Best for: Serious athletes, women who work out 4+ times per week, anyone willing to invest in purpose-built athletic underwear
What NOT to Wear Under Leggings
- Regular cotton underwear: Cotton absorbs moisture and stays wet. During a sweaty workout, wet cotton against your skin creates a breeding ground for bacteria and yeast. It also bunches, shifts, and creates obvious panty lines under tight fabric.
- Thick-seamed or lace underwear: Any underwear with raised seams, lace trim, or textured fabric will show through leggings. The ridges create visible lines that are impossible to hide under fitted fabric.
- Loose-fitting underwear: Underwear that does not fit snugly will bunch up, ride, and shift during movement. Under leggings, this creates visible lumps and uncomfortable friction points.
- Bright or patterned underwear under light leggings: If your leggings are anything lighter than black, bright underwear will show through. Nude or skin-tone underwear is the safest choice for opacity under any legging color.
The Color Rule
Underwear color matters more than most women realize when wearing leggings:
| Legging Color | Best Underwear Color | Why |
|---|---|---|
| Black or very dark | Black or nude | Black blends with fabric; nude is invisible if fabric is borderline sheer |
| Navy, charcoal, dark colors | Nude or matching dark | Nude disappears; matching dark blends in |
| White or cream | Nude (your skin tone) | White underwear actually shows more than nude under white fabric |
| Light colors and pastels | Nude (your skin tone) | Any non-nude color risks showing through |
| Medium colors | Nude | The safest universal choice for medium tones |
The universal rule: When in doubt, wear nude underwear that matches your skin tone. This works under every legging color because it blends with your body rather than the fabric.
Fabric Guide for Underwear Under Leggings
- Nylon-spandex blends: The best overall choice for workout underwear. Silky smooth (invisible under leggings), moisture-wicking, quick-drying, and stretchy enough to move with your body. Gymshark's seamless underwear line and similar athletic brands use this blend.
- Microfiber: Ultra-smooth and nearly invisible under tight fabrics. Excellent for everyday wear under leggings. Less moisture-wicking than nylon-spandex but adequate for low-to-moderate intensity activities.
- Bamboo viscose: Naturally moisture-wicking, antimicrobial, and soft. An excellent natural-fiber alternative for women who prefer to avoid full synthetics. Boody and similar eco-conscious brands specialize in bamboo underwear designed for activewear use.
- Modal: Ultra-soft and breathable with good moisture management. A step up from cotton in both comfort and performance. Works well for lower-intensity activities and everyday athleisure wear.
- Cotton: Fine for casual everyday wear but not recommended for workouts. Absorbs moisture, dries slowly, and increases infection risk during sweaty exercise. If you strongly prefer cotton, look for cotton-blend options with at least 20% synthetic for better moisture management.
Special Considerations
During Your Period
Period-proof underwear brands (like Thinx, Knix, and Modibodi) have released workout-specific lines designed to be worn under leggings during your period. These provide leak protection without the bulk of traditional pads, and many are thin enough to stay relatively invisible under fitted leggings. Combined with a tampon or cup for heavier days, period-proof underwear provides a confidence-boosting backup layer.
For Pregnancy and Postpartum
During pregnancy and postpartum recovery, comfort and support take priority over VPL concerns. Choose soft, high-rise underwear with a wide, non-binding waistband that sits comfortably over your belly. Nylon-spandex or bamboo blends provide the stretch needed to accommodate your changing body while staying smooth under maternity leggings.
For Sensitive Skin
If you experience irritation from synthetic fabrics, bamboo viscose or TENCEL modal are the gentlest options. Both are naturally hypoallergenic, antimicrobial, and softer than any synthetic blend. Avoid any underwear with dyed elastic bands against sensitive areas -- look for designs where the elastic is encased in fabric rather than sitting directly against skin.
How Your Leggings Affect the Decision
The leggings themselves matter as much as the underwear you choose:
- Leggings with a cotton gusset: These are designed to be worn without underwear. The cotton panel provides moisture absorption and hygiene protection. Many quality activewear leggings include this feature. The Avurer Viva High-Waist Leggings include this thoughtful construction detail.
- Thick, opaque leggings: Safer for going commando because the fabric provides adequate coverage and protection from gym equipment bacteria. Nylon-spandex construction like the Avurer LuxeLegs provides this density.
- Thin or sheer-prone leggings: Wear underwear. Thin fabric does not provide adequate barrier protection, and the underwear layer adds both modesty and hygiene benefits.
- Seamless leggings: The Avurer FlexFit Seamless Leggings have fewer seams to show through underwear, making them more forgiving if your underwear is not perfectly invisible.
Post-Workout Hygiene (Regardless of What You Wear Under)
Whether you go commando or wear underwear, these hygiene practices are non-negotiable:
- Change out of sweaty leggings as soon as possible: "You want to avoid lingering in wet clothes, as that can elevate your risk of yeast infections," advises Dr. Rosser. Excess moisture also leads to painful chafing.
- Shower after every workout: Regardless of underwear choice, post-workout showering removes sweat, bacteria, and dead skin cells that accumulate during exercise.
- Wash leggings after every workout: Especially important if you go commando. Wearing unwashed leggings for a second workout introduces yesterday's bacteria back against your skin.
- Air dry leggings and underwear: High dryer heat degrades both the elastic in underwear and the spandex in leggings. Air drying preserves the fit, fabric integrity, and antimicrobial properties of both.
Frequently Asked Questions
Is it safe to go commando under leggings?
Yes, according to OB-GYNs. Going commando is perfectly safe as long as your leggings are opaque, have a built-in gusset for moisture absorption, and you wash them after every wear. The key is ensuring the fabric is thick enough to act as a barrier between your body and gym equipment. Dr. Rosser and Dr. Osmun both confirm there are no medical drawbacks to either choice -- it is a matter of personal preference.
What is the best underwear to avoid panty lines under leggings?
Seamless thongs with laser-cut or bonded edges create the smoothest, most invisible line under leggings. For more coverage, seamless Brazilian or bikini cuts in microfiber or nylon-spandex are nearly as invisible. The most important features are: no raised seams, bonded or laser-cut edges, a color that matches your skin tone, and a rise that matches your leggings' waistband height.
Should I wear a thong to the gym?
It depends on the activity and your body's sensitivity. Thongs provide the best VPL elimination but can cause friction and microabrasions during high-impact exercise. Dr. Osmun notes it may actually be "safer to go without underwear than to wear a thong during exercise" for this reason. If you do wear thongs to the gym, choose soft, seamless options and reserve them for lower-impact activities like yoga, pilates, and light lifting.
What color underwear should I wear under leggings?
Nude underwear that matches your skin tone is the safest choice under any legging color. Nude disappears against your body rather than creating contrast with the fabric. Under black leggings, either black or nude works. Under white or light leggings, always choose nude -- white underwear actually shows more than nude because it creates its own visible contrast against your skin.
Do I need special athletic underwear for the gym?
You do not need it, but purpose-built athletic underwear performs noticeably better than regular underwear for workouts. Athletic underwear uses moisture-wicking fabrics, flat seams, body-mapped construction, and antimicrobial treatments that regular underwear lacks. If you work out frequently, investing in 3-4 pairs of quality athletic underwear specifically for gym use is worthwhile for both comfort and hygiene.
Wear What Works for You
There is no universally correct answer to what to wear under leggings. The right choice depends on your body, your activity, your leggings' construction, and your personal comfort. What matters is making an informed decision rather than a default one.
Choose moisture-wicking fabrics. Match your underwear color to your skin tone. Wash everything after every workout. And most importantly -- do not let underwear anxiety distract you from the workout itself.
Ready for leggings designed with comfort in mind? Browse Avurer's full collection -- leggings with built-in gussets, sports bras, tank tops, hoodies, joggers, and jackets designed for women who want to focus on their workout, not on what is happening underneath.
