Outgro Pain Relief Drug Interactions: What to Avoid and What to Tell Your Doctor

Even though Outgro Pain Relief is an OTC product you can buy without a prescription, it can interact with other medications. Benzocaine 20% topical has 55 known drug interactions, including 2 major interactions. Knowing which medications to watch out for — and what to tell your healthcare provider — can prevent serious complications.

Why Do Drug Interactions Matter With an OTC Topical Product?

Many people assume that because Outgro is applied to the skin and available without a prescription, it can't really interact with their other medications. This assumption is incorrect. Benzocaine, even when applied topically, is absorbed into the bloodstream to some degree. And more importantly, some drug interactions work through shared physiological mechanisms rather than direct chemical reactions — meaning the combination can cause serious side effects even if blood levels of benzocaine remain low.

The Most Important Interaction: Nitrates and Nitrites

The highest-risk drug interaction with benzocaine involves medications that contain nitrates or nitrites. These medications increase the risk of methemoglobinemia — the same serious blood disorder that benzocaine itself can cause. Together, the risk is significantly elevated.

Common nitrate/nitrite-containing medications include:

Nitroglycerin (for angina) — patch, tablet, or spray forms

Isosorbide mononitrate and isosorbide dinitrate (for heart failure and angina)

Amyl nitrite (used medically for cyanide poisoning; also used recreationally)

If you are taking any nitrate or nitrite medication, tell your doctor or pharmacist before using Outgro Pain Relief or any benzocaine product.

Other Medications That Increase Methemoglobinemia Risk

Beyond nitrates, several other medications can increase the risk of methemoglobinemia when combined with benzocaine:

Dapsone — used for leprosy, malaria prophylaxis, and some skin conditions; also can cause methemoglobinemia on its own

Prilocaine — another local anesthetic that carries methemoglobin risk; additive when used with benzocaine

Sulfonamide antibiotics (sulfamethoxazole, etc.) — can increase methemoglobin formation in combination with oxidizing agents

Phenacetin — historical analgesic with methemoglobin-producing properties

Interactions With Other Topical Anesthetics

Using benzocaine together with other topical anesthetics on overlapping areas increases the total amount of anesthetic absorbed and may increase the risk of both methemoglobinemia and systemic toxicity. Avoid using Outgro Pain Relief at the same time and on the same area as other benzocaine products, lidocaine products, or other local anesthetics unless directed by a doctor.

The Disease Interaction: Methemoglobinemia History

Outgro Pain Relief has one known disease interaction: methemoglobinemia. If you have ever had methemoglobinemia, you must not use benzocaine topical products including Outgro. This is an absolute contraindication.

What to Tell Your Doctor Before Using Outgro Pain Relief

Before using Outgro Pain Relief, tell your doctor or pharmacist if you:

Have ever had methemoglobinemia or have a family history of it

Are taking any nitrate or nitrite medications (especially nitroglycerin for heart conditions)

Have asthma, COPD, emphysema, or other lung disease

Have heart disease or cardiovascular conditions

Have G6PD deficiency or pyruvate kinase deficiency

Are taking dapsone, sulfonamide antibiotics, or other oxidizing medications

Are using other topical anesthetics on the same or nearby areas

Are pregnant or breastfeeding

Practical Tips to Minimize Interaction Risk

Use the smallest amount needed and don't exceed 4 applications per day

Do not apply to large areas of skin or broken/damaged skin (increases absorption)

Do not combine with other topical anesthetics on the same area

Watch for methemoglobinemia symptoms during and after use

For a complete guide to Outgro's side effect profile, see: Outgro Pain Relief Side Effects: What to Expect and When to Call Your Doctor

If you're still looking for Outgro Pain Relief near you, medfinder can call local pharmacies to find which ones have it in stock and text you the results.