Many people have experienced their lips suddenly looking darker or more red after licking them. This seemingly mysterious phenomenon has a simple scientific explanation behind it that relates to the composition of saliva and how it temporarily changes the appearance of your lips. In this article, we’ll explore the reasons why licking your lips makes them appear darker.
What causes lips to darken when licked?
The main reason your lips darken after licking them is because saliva is hydrating and temporarily plumps your lips. Here’s a more in-depth look at what’s going on:
- Saliva contains water and enzymes that provide moisture and hydration to your lips.
- When your lips are hydrated, they become more plump and smooth due to the water content.
- Plumper lips mean there is increased blood circulation in the area, leading to a redder/darker appearance.
- The natural pigments in your lips also become more pronounced with increased hydration.
So in essence, the temporary color change is caused by the hydrating action of saliva bringing out the natural pinkish/reddish tone of your lips more noticeably. The effect is temporary and fades as the moisture gets absorbed by your lips.
The composition of saliva
To better understand why saliva hydrates your lips so quickly, let’s take a look at what it’s made of:
- Water – Up to 99% of saliva is water.
- Electrolytes – Including sodium, potassium, calcium and chloride.
- Enzymes – Such as amylase and lipase to help digest food.
- Antibodies – Immunoglobulins that protect against pathogens.
- Mucus – Glycoproteins that lubricate the mouth.
The high water content is the key driver of the hydrating effect. But the electrolytes, enzymes and other components also assist with the temporary plumping effect.
When you spread this mix of water and compounds over your lips by licking them, it provides an immediate hydration boost. The liquid gets quickly absorbed into the sensitive skin of the lips, causing them to appear smoother and fuller.
How the vascular anatomy of lips contributes
Another factor at play is the anatomy of lips and how blood circulates through them. Here are some key points about the lip structure:
- Lips have a high concentration of small blood vessels close to the skin.
- The blood vessels dilate and engorge with blood easily, which is why lips redden so readily.
- Lips lack sebaceous glands and sweat glands, so they depend on moisture from saliva.
- The skin of the lips is thin with little keratin, making it permeable to saliva.
This high vascularity coupled with lack of natural lubrication is why your lips are so quick to change color when licked. The saliva hydrates, while the blood vessels swell and engorge in response.
Overall, the anatomy of lips makes them highly sensitive to changes in hydration and blood flow. A small action like licking quickly shows up as a change in appearance.
Pigments in the lips
In addition to moisture and blood flow changes, the natural pigments in lips also play a role in the color change. Here are the key compounds:
- Melanin – Brown pigment that protects from sun exposure.
- Carotene – Yellow/orange pigment from plant sources.
- Hemoglobin – Red pigment from blood that gives lips their reddish hue.
When your lips are well hydrated after licking, these natural pigments become more pronounced and vibrant. The increased blood flow also amplifies the reddish hemoglobin tone.
This is why your lips may appear darker or more red/pink after licking, rather than just smoother or plumper. The pigments are displaying more visibly.
Does licking damage your lips?
While licking your lips can make them appear darker temporarily, some may wonder if it damages your lips over time? Here are some points on this:
- Occasional licking is fine, but chronic licking and biting of lips can damage skin.
- Saliva provides temporary hydration but dries up fast. Long term licking strips away natural oils.
- Over time it can lead to dryness, scaling, redness, swelling and skin erosion.
- Damaged lips from chronic licking are prone to infection from oral bacteria.
- Using lip balm and avoiding temptation to lick/bite is better for long term lip care.
So while an occasional lick is harmless, it’s best not to overdo it. Let the natural oils in your lips and products like petroleum jelly provide long-lasting hydration instead.
When to see a doctor
While short term lip darkening from licking is normal, sometimes persistently dark lips can indicate an underlying issue. See your doctor if your lips stay unusually dark and you also notice:
- Dryness, cracking, redness or swelling.
- Changes in lip texture or appearance.
- Sores, spots or nodules on the lips.
- Discoloration that spreads beyond your lips.
- Unexplained weight loss.
- Numbness or pain in the lips.
Some of the possible causes that need medical assessment include:
- Dehydration – Insufficient fluid intake.
- Vitamin deficiency – Such as iron (anemia) or B12 (pernicious anemia).
- Oral cancer – Persistent lip changes need cancer evaluation.
- Melanoma – Pigmented lesions on the lips.
- Hemangioma – Benign vascular lesion appearing as a mole.
- Lichen planus – An inflammatory skin condition that can involve lips.
So while short term darkening from licking is normal, persistent dark or discolored lips warrant medical investigation.
When to use lip products
If your lips are prone to drying out, you may need more intensive lip care through topical products:
- Use gentle liquid cleansers rather than soap to avoid stripping oils.
- Use lip balms and petroleum jelly to hydrate and seal in moisture.
- Lip scrubs can exfoliate away dry flakes to improve lip appearance.
- Avoid matte lipstick formulas that dry out the lips.
- Apply sunscreen to protect delicate lip skin from sun damage.
- Try overnight masks to deeply nourish and smooth rough lips.
These simple measures can improve the tone and texture of your lips. Use them preventatively before your lips become extremely dry or discolored.
Top lip balm ingredients for hydration
When shopping for the best lip balms, look for these effective hydrating ingredients:
- Petroleum jelly – Seals in moisture to prevent evaporation.
- Shea butter – Softens and smoothes rough, dry lips.
- Beeswax – Acts as an occlusive barrier.
- Dimethicone – Improves texture and hydrates.
- Glycerin – Draws in and binds moisture.
- Lanolin – Emollient wax that mimics natural oils.
Avoid lip products with irritants like menthol, camphor and phenol if you have sensitive lips prone to darkness. Stick to nourishing formulations made for very dry lips.
Other causes of lip darkening
While licking is the most common cause of temporary lip darkness, there are some other possible reasons your lips may appear darker:
Genetics
Some people just naturally have darker lips due to their genetics and ethnic background. Higher amounts of melanin pigment leads to richer lip tones. This non-pathological pigmentation is a normal variation.
Smoking
Cigarette smoking can stain and discolor lips over time, leading to a darker, duller appearance. It also depletes moisture and leads to thinning of lip skin. So smoked lips tend to look darker as well as drier.
Sun exposure
UV radiation from the sun causes melanin pigment in your lips to oxidize and darken over time. Just as skin tans in the sun, your lips can also tan if exposed for prolonged periods without sun protection.
Drug side effects
Certain prescription drugs like antibiotics and chemotherapeutics can cause lip hyperpigmentation. Minocycline, doxorubicin and hydroxyurea are examples. Consult your doctor if you suspect drug-related lip color changes.
Lead exposure
Exposure to lead through pollution, paint or tainted food/water can accumulate in the body and manifest as grey, darkened lips. It is an important sign of possible lead poisoning.
Lichen planus
This chronic inflammatory condition affects mucus membranes in the mouth and skin. It can result in scaly, discolored lesions on the lips and intraoral surfaces.
Hemangiomas
These are benign vascular growths comprised of overgrown blood vessels. They appear as reddish-purple nodules or patches that may bleed if injured. Lip hemangiomas can vary greatly in size.
Angular cheilitis
This common inflammatory condition affects the corners of the mouth, causing cracks, redness and crusting. It can develop into swollen, darkened patches at the lip corners.
When to see a doctor
Consult your physician or dermatologist if your lips remain abnormally dark or change color and you don’t know why. Darkening not clearly linked to temporary hydration changes from licking likely needs medical assessment. Seek timely diagnosis and treatment for:
- Pain, bleeding, ulcerations or sores.
- Persistent cracking, roughness or scaliness.
- Asymmetric color changes that are new or spreading.
- Discoloration extending beyond your lips.
- Associated symptoms like fever or weight loss.
- Risk factors like smoking or sun damage.
- No improvement with over-the-counter balms.
Don’t ignore stubborn lip darkening or wait for it to resolve on its own. Prompt diagnosis of any underlying condition can help avoid complications.
When to switch lip products
Sometimes darkening of lips is caused by an allergic reaction or irritation rather than any internal disease. Clues that your lip product may be to blame:
- Issue started after using a new product.
- Only occurs where lip product is applied.
- Appears shortly after each application.
- Associated symptoms like redness, stinging, swelling.
The most common irritants in lipsticks are fragrances, preservatives and dyes. However, any ingredient can potentially cause a reaction.
If your lips darken or change color after using a lipstick, gloss or balm, switch products. Opt for a fragrance-free, gentle formula marketed for sensitive skin instead. Also exfoliate lips to remove any residual allergens or irritants.
Medical treatments for lip discoloration
If your lip darkening is linked to an underlying medical condition, your doctor may recommend:
Medications
– Hydrocortisone cream to reduce inflammation from conditions like lichen planus.
– Antifungal medication for fungal infections.
– Antiviral medication for herpes infections.
– Isotretinoin or other retinoids for dark pigmentation disorders.
– Laser therapy to lighten hyperpigmentation.
Procedures
– Cryosurgery to freeze lesions off.
– Surgical excision for potentially cancerous growths.
– Laser treatment to remove dark melanin deposits.
– Chemical peels to reduce hyperpigmentation gradually.
Lifestyle changes
– Smoking cessation and limiting sun exposure if those caused discoloration.
– Avoiding potential allergens or irritants.
– Drinking plenty of fluids if dehydration is contributing.
– Taking nutritional supplements if deficiency is suspected.
Follow your doctor’s advice diligently to resolve discolored lips. Request referral to a dermatologist or oral medicine specialist if the cause is unclear.
Preventing lip darkening
You can take proactive steps to avoid sudden darkening of lips from licking as well as long term lip discoloration:
- Apply lip balm frequently to avoid licking dry lips.
- Use gentle cleansers and moisturizers suitable for sensitive skin.
- Exfoliate lips weekly with a soft scrub to improve tone and texture.
- Avoid very matte lipsticks that cling to dry flakes.
- Wear SPF lip balm during sun exposure.
- Stay hydrated by drinking adequate water.
- Take a multivitamin to prevent nutritional deficiencies.
- Don’t smoke and avoid secondhand smoke.
- See your doctor at the first sign of persistent lip changes.
Caring properly for your lips and having regular skin cancer screenings can help nip any issues in the bud before they progress.
Conclusion
Licking your lips makes them appear darker temporarily due to hydration and blood flow changes. But persistent lip discoloration or damage from chronic licking needs evaluation. Seek treatment for medical conditions like oral cancer, vitamin deficiencies, allergies and more. Protect your lips from sun exposure and irritants. Overall, maintaining good lip health prevents unpleasant color changes down the line.