The single most important thing to do before red light therapy is show up with clean, bare skin. Makeup, sunscreen, and heavy creams create a physical barrier that blocks or scatters the light before it reaches your cells. Beyond that, a handful of preparation steps can make a real difference in how much benefit you get from each session.
Clean Your Skin Thoroughly
Red and near-infrared light needs a clear path into your skin. Any layer sitting on the surface, whether it’s foundation, SPF, a thick moisturizer, or even a film of sweat and oil from earlier in the day, reduces how much light actually penetrates. Wash the treatment area with a gentle cleanser and pat dry. If you’re treating your face, arrive bare-faced.
Light, water-based products like hyaluronic acid serums are fine if applied a few hours earlier, but rich occlusive creams and sunscreen should be skipped entirely on treatment day. The goal is a surface with nothing reflective or opaque between the light and your skin.
Pause Harsh Actives 24 to 72 Hours Before
Retinol, AHAs, BHAs, benzoyl peroxide, and alcohol-based toners all increase your skin’s sensitivity to light. Using them right before a session raises the risk of redness, irritation, or an exaggerated inflammatory response that works against what the therapy is trying to do.
A good rule of thumb: stop exfoliating acids, physical scrubs, and strong acne spot treatments 48 to 72 hours before your session. For retinol and alcohol-based toners, 24 hours is the minimum buffer. Resume them at least 24 hours after treatment as well, giving your skin time to settle on both sides of the session.
Remove Clothing Over the Treatment Area
Red light therapy works best on bare skin. Fabric scatters and absorbs light, reducing the dose that reaches deeper tissue. Dark colors, thick materials, and shiny or tightly woven synthetics are the worst offenders, blocking significant amounts of both visible red and near-infrared wavelengths.
If you can’t fully undress (in a clinic setting, for example), choose light-colored, loose-fitting, breathable fabrics like white cotton or linen. These allow more light through than dark or heavy alternatives. But direct skin exposure is always the most effective option, so remove what you can.
Protect Your Eyes Properly
This is the preparation step most people either skip or get wrong. Most red light panels emit near-infrared wavelengths (700 to 1,100 nm) alongside visible red light, and near-infrared poses a real concern for your eyes. Your eyelids transmit a meaningful portion of near-infrared light directly to the retina, so simply closing your eyes is not adequate protection.
You need goggles specifically rated for photobiomodulation or LED/laser therapy in the 600 to 1,100 nm range, with an optical density (OD) of at least 3. Regular sunglasses, even dark polarized pairs, are not designed to block these wavelengths and will not protect you.
Eye protection is especially important when:
- Your face is in the treatment zone and the panel emits near-infrared light (most full-body panels do)
- You’re closer than 6 inches to a high-powered panel
- Sessions last longer than 10 minutes with direct facial exposure
- You have an existing eye condition like macular degeneration, cataracts, or a history of retinal problems
- You take photosensitizing medications
If you’re only treating your back, legs, or other areas with your face turned away from the panel, the risk drops considerably. But having a proper pair of goggles on hand is a smart baseline habit.
Check Your Medications
Certain medications increase your skin’s sensitivity to light in ways that can cause unexpected reactions during red light therapy. The most common culprits include tetracycline and doxycycline (antibiotics frequently prescribed for acne or infections), isotretinoin (the oral acne medication), certain antifungals, lithium, some antipsychotics, and chemotherapy drugs. If you’re on immunosuppressants or anticoagulants, those also warrant a conversation with your prescribing doctor before you start sessions.
This doesn’t necessarily mean you can’t use red light therapy, but your provider needs to know what you’re taking so they can adjust the approach or confirm it’s safe.
Choose the Right Time of Day
Red light therapy influences your body’s hormonal rhythms, and timing your session can work for or against you depending on your goals. Sessions 30 to 60 minutes before bed can encourage melatonin release and improve sleep quality. However, using red light too close to the moment you’re trying to fall asleep, or leaving a device on overnight, can actually suppress melatonin and disrupt rest.
Morning or midday sessions work well for energy, muscle recovery, or skin goals where sleep timing isn’t a factor. There’s no single “best” time that applies to everyone, but consistency matters more than perfection. Pick a time you can stick with and keep your sessions regular.
Set Up Your Distance
Before you turn the device on, know where to position yourself. The therapeutic sweet spot for most panels falls between 6 and 12 inches from the light source. For deeper targets like muscle soreness or joint pain, closer is better: 6 to 8 inches. For general skin health or wellness, 8 to 12 inches provides good coverage without excessive intensity.
Positioning matters because light intensity drops quickly with distance. Sitting too far away means your tissue may not receive enough energy to trigger a meaningful cellular response. Too close, and you risk overstimulating the skin, especially if you’ve recently used active skincare ingredients. Check your specific device’s guidelines, since output power varies significantly between products.
Know When to Skip a Session
A few situations call for holding off on red light therapy entirely. Active cancer is the most significant: multiple lab studies show that low-level light exposure can accelerate the growth of cancer cells, and professional guidelines advise against treating over or near a known malignancy. If you’re undergoing cancer treatment, this is a conversation to have with your oncologist before proceeding.
Pregnancy is another common contraindication listed by most device manufacturers. Research on light therapy during pregnancy is limited, and fetal exposure hasn’t been adequately studied. The standard recommendation is to avoid treating the abdomen during pregnancy.
Freshly sunburned or broken skin, active infections in the treatment area, and recent cosmetic procedures (like chemical peels or laser resurfacing) are also reasons to wait. Let your skin return to a calm baseline before adding light therapy into the mix.