A pitch burn is a skin reaction caused by contact with tree resin (pitch) or other plant saps, often made worse by sun exposure. It can look and feel like a genuine burn, with redness, pain, blistering, and dark discoloration that lingers for weeks or even months. Despite the name, it’s not a thermal burn. It’s a chemical irritation triggered by compounds in the sap, sometimes activated by ultraviolet light.
How Tree Pitch Damages Skin
Tree pitch and plant saps contain a range of naturally occurring chemicals that can irritate or injure skin. The two main pathways depend on the type of plant involved.
Many plants in the citrus, fig, and carrot families produce compounds called furanocoumarins. These chemicals are harmless in the dark, but when ultraviolet light (specifically UVA rays) hits them on your skin, they become activated and trigger a reaction called phytophotodermatitis. This is not an allergic response. It’s a direct chemical burn caused by the interaction between the plant compound and sunlight. Anyone can get it, regardless of skin type or allergy history.
Coniferous trees like pines, spruces, and firs produce a different kind of resin rich in terpenes. Pure terpenes are not usually irritating on their own, but they oxidize when exposed to air. These oxidized byproducts can cause contact irritation and, in some people, allergic skin reactions. This type of pitch burn tends to cause redness, itching, and mild swelling rather than the dramatic blistering associated with sun-activated sap.
What a Pitch Burn Looks and Feels Like
The reaction typically unfolds in stages. At first, the skin may look completely normal. Then, within 24 to 48 hours (sometimes up to 3 days), redness appears along with a burning or stinging sensation. The pattern of the rash often follows the exact shape of the sap contact, which can look like streaks, drips, or handprints.
In moderate to severe cases, the redness progresses to swelling and fluid-filled blisters. These blisters can discharge clear fluid and may peak in severity around 72 hours after exposure. The affected skin feels painful rather than itchy, though some people experience both. One case involving fig sap documented blisters forming across both forearms within 24 hours, with pain and swelling continuing to worsen over the following day.
The most persistent phase is discoloration. After the initial redness and blistering subside, dark patches develop where the skin was damaged. This post-inflammatory hyperpigmentation typically appears one to two weeks after exposure and can last months. In some cases, the darkened skin persists for one to two years. Deeper pigment changes, which appear more blue-gray than brown, can take even longer to fade or may become permanent without treatment.
Plants Most Likely to Cause It
The sun-activated type of pitch burn is most commonly caused by plants that produce furanocoumarins. These include fig trees (a frequent culprit, especially when pruning or harvesting), limes and other citrus fruits, wild parsnip, giant hogweed, celery, and Queen Anne’s lace. Fig sap is particularly notorious because casual gardeners often don’t realize the milky latex is phototoxic.
The resin-based type comes from conifers: pine, spruce, fir, and cedar. Handling firewood, climbing trees, or doing forestry work without gloves are common scenarios. The sticky pitch is hard to wash off, which prolongs skin contact and increases the chance of irritation.
How to Remove Pitch From Skin
Getting the sap off quickly is the single most important step. The longer it sits on your skin (and the more sun exposure you get while it’s there), the worse the reaction will be.
- Cooking oil and sugar: Rub vegetable, olive, or canola oil onto the affected area to dissolve the sap, then use sugar as a gentle abrasive to scrub it away. This is effective for both fresh and slightly hardened resin.
- Peanut butter or olive oil alone: The oils in either product break down the sap’s sticky bonds. Apply, let it sit briefly, then wipe clean and wash with soap and water.
- Alcohol-based hand sanitizer: The alcohol dissolves fresh sap quickly. Apply generously, rub, and rinse. This works best before the resin has fully hardened.
- Vinegar or baking soda paste: Both are mildly effective and safe for sensitive skin. Apply to the sap and scrub gently.
Avoid using harsh solvents like WD-40 or mineral spirits unless the sap is fully hardened and nothing else works. These can further irritate already-damaged skin. If you do use them, wash thoroughly with soap and water immediately afterward.
Treating the Skin Reaction
If you already have redness, pain, or blistering, the priority shifts from sap removal to burn care. Cool compresses can help with pain and swelling in the first 24 to 48 hours. Over-the-counter hydrocortisone cream reduces inflammation for mild cases. For more severe blistering, a doctor may prescribe a stronger topical corticosteroid.
Keep blistered skin clean and covered to prevent infection. Resist the urge to pop blisters, as the fluid-filled barrier protects healing skin underneath. Pain relievers like ibuprofen can help manage discomfort and reduce swelling during the acute phase.
Protecting the affected area from further sun exposure is critical. UV light will worsen the reaction if furanocoumarins are still present on the skin, and it can deepen the hyperpigmentation that follows. Keep the area covered or use high-SPF sunscreen during the entire healing period, which may stretch for several months.
How Long Recovery Takes
The acute symptoms, meaning the redness, pain, and blistering, generally resolve within one to two weeks. The skin may peel as it heals, similar to a sunburn. What catches most people off guard is the discoloration that follows. The dark patches that develop are not scars in the traditional sense but rather excess pigment deposited in the skin as part of the inflammatory response.
Surface-level hyperpigmentation (tan to dark brown) typically fades over several months without treatment, though it can take up to a year. Deeper pigment deposits with a blue-gray tone are more stubborn and may require professional treatment to resolve. People with darker skin tones tend to develop more pronounced and longer-lasting hyperpigmentation. Consistent sun protection on the affected area speeds fading and prevents the discoloration from deepening further.