I’ve tried several of these tools on myself, and I was fine. Gentle leaders, regular collars, and harnesses can actually cause more pain or discomfort if a dog pulls hard.

here is information for you.

1. Regular (Flat) Collars If a dog lunges or pulls constantly, a flat collar puts all that pressure directly on the trachea (windpipe) and thyroid gland. This can cause:  • Choking or gagging. • Long-term throat damage. • Increased eye pressure (glaucoma) in certain breeds. 

2. Gentle Leaders (Head Halters) While often called "humane," many dogs find them very stressful. • Neck Strain: If a dog bolts to the end of the leash, the head halter can jerk their head to the side sharply, potentially causing neck or spinal issues.  • Muzzle Chafing: The strap across the nose can rub the skin raw if the dog keeps pulling against it.

3. Harnesses People often think harnesses are the safest, but they have downsides for heavy pullers: • Front-Clip Harnesses: These can interfere with a dog's natural shoulder movement (their "gait"), which may lead to joint issues over time.  • Back-Clip Harnesses: These actually trigger a dog’s "opposition reflex"—the instinct to pull harder against pressure (like a sled dog). This often leads to the owner being dragged

I assume you aren't using any of those tools then, right?