RN
Most writing on this subject sells the experience. The useful version is duller and more practical: a lubricant is a substance you are putting in contact with mucous membrane, latex, and possibly silicone, and only some combinations of those four things work.
Get the compatibility right and the rest is preference. Get it wrong and you can degrade a condom, ruin a toy, or spend two days regretting a fragrance additive. So the sensible order is base type first, then feel.
The three bases, and what each one breaks
Water-based. The default, and the only one with no compatibility problems at all — safe with latex, safe with polyisoprene, safe with every toy material. It rinses off, it does not stain, and it is the correct answer whenever you are unsure. The trade-off is that it is mostly water, so it evaporates and absorbs. Longer sessions need reapplication, and many formulations pass through a tacky phase on the way to drying out. A splash of water usually revives them rather than requiring more product.
Silicone-based. Lasts far longer, because there is nothing in it to evaporate, and it is unaffected by water — the reason it is the usual choice for anything happening in a shower or bath. It is condom-safe. Its one real restriction is that silicone lubricant and silicone toys are chemically related enough that prolonged contact can degrade the toy's surface, leaving it tacky or pitted. Toys made of glass, stainless steel or ABS plastic are unaffected. It also takes soap to remove and can mark fabric.
Oil-based. Includes both purpose-made products and kitchen oils. The critical fact here is not optional: oils degrade latex, and a latex condom exposed to oil can fail. The same applies to latex gloves and dams. If a barrier method is involved in any way, oil is off the table. Where no barrier is involved it is durable and good for massage, though it is harder to wash out of textiles and some people find it harder to clear from the body afterwards.
Hybrid formulations exist that blend a water base with a small amount of silicone. They inherit some longevity without the toy restriction, but the compatibility depends on the specific formulation rather than on the category, so the label is the authority.
Additives are where the irritation comes from
Base type rarely causes trouble. Additives frequently do.
Warming and cooling products work by adding a compound that stimulates nerve endings — the sensation is real but it is a chemical effect on tissue, and vaginal and anal tissue is considerably more sensitive than the forearm most people imagine when they read the label. Flavoured products contain sweeteners. Fragranced products contain fragrance, which is among the more common contact irritants in any personal-care category.
Glycerin appears in a great many water-based products and is a frequent subject of debate, particularly regarding whether it contributes to yeast overgrowth in people who are prone to it. The honest position is that individual susceptibility varies and the evidence is not clean enough to state a rule. If you get recurrent thrush and cannot identify a trigger, a glycerin-free product is a cheap thing to test.
Preservatives are necessary — an unpreserved water-based gel would not be shelf-stable — but they are also the ingredient class most often implicated in irritation. None of this makes additives dangerous. It makes them the first thing to eliminate when something goes wrong.
A patch test costs nothing
Before a new product goes anywhere sensitive, put a small amount somewhere ordinary and leave it for a few hours. Inner forearm is the conventional spot. This will not catch every reaction, because genital tissue is more permeable than arm skin, but it catches the obvious ones at no cost.
If a product stings, burns, or leaves anything itchy or raw, stop using it and wash it off. That is a reaction, not a sign it is working.
Dryness that is not situational
There is a difference between wanting more glide and having a body that has stopped producing lubrication it used to produce. Lubricant addresses the first. The second is a medical question with several common causes — hormonal changes around menopause, breastfeeding, certain contraceptives, antihistamines, antidepressants and other medications, and a number of conditions unrelated to any of those.
Vaginal moisturisers are a separate product category from lubricants, used on a schedule rather than during sex, and they exist precisely because ongoing dryness needs something different from an on-demand product. There are also prescription options. All of that is a conversation with a doctor or pharmacist, not something to work out from an article.
The same applies to pain. Discomfort during sex is common, which is not the same as it being normal, and it has causes that lubricant does not fix and can mask. If more glide does not resolve it, the problem is not friction.
Storage, and the small stuff
Heat and light degrade these products, which is why the bathroom shelf above a shower is a poor location despite being the obvious one. Somewhere cool, dry and dark is better. They carry expiry dates for a reason — preservative systems do not last forever, and an old bottle is a plausible explanation for a product that suddenly irritates when it never used to.
Anal use has a genuinely different requirement, since there is no natural lubrication involved at all. More is needed, it needs reapplying, and a thicker product generally performs better than a thin one.
The short version
If you want one product that always works, buy an unscented, unflavoured, additive-light water-based lubricant. It is compatible with everything, it is the least likely to irritate, and its only drawback is that you will use more of it.
Everything past that is optimisation: silicone for duration and for water, oil where no barrier is involved, additives if you have tested them and your body is fine with them. And if the reason you are reading this is that something changed — new pain, new dryness, new irritation — that is worth raising with a clinician rather than solving with a purchase.