I'm sorry to hear about the irritation on your forehead after sex. Skin irritation in that area could be due to several reasons such as an allergic reaction, contact dermatitis from soaps, lubricants, or condoms, or even a mild infection.

Here are some steps you can take:

• Avoid any new products on your face or genital area that might be causing irritation, such as scented soaps, lotions, or lubricants.
• Keep the area clean and dry using gentle, fragrance-free cleansers.
• Avoid scratching or rubbing the irritated skin to prevent worsening.
• If you suspect an infection or if the irritation persists beyond a couple of weeks, worsens, or is accompanied by other symptoms like pain, swelling, or discharge, it is important to see a dermatologist (skin specialist) for a proper evaluation.

Since the irritation started after sexual activity, it might also be helpful to consider if any sexually transmitted infections (STIs) could be involved. A consultation with a dermatologist or a sexual health specialist can help determine the cause and provide appropriate treatment.

Please avoid self-medicating with antibiotics or other medications without a doctor's advice, as inappropriate use can lead to resistance or side effects.

If you experience severe symptoms such as intense pain, spreading redness, fever, or blistering, seek immediate medical attention.

Recommendation: Please consult a dermatologist or a sexual health specialist for an accurate diagnosis and personalized treatment plan.To narrow down potential causes, we will need some more information.I understand you're dealing with skin irritation on your forehead after sex that started a couple of weeks ago. To help me understand better, could you please tell me your age and gender?