How much lubricant you actually need
Almost everyone uses too little, and the ones who use too much are not a problem worth solving. The amount is larger than the bottle suggests, and water-based needs topping up on a schedule rather than when things have already gone wrong.
The amount
Start with roughly a teaspoon, or a line of it about the length of your finger. That is the starting point, not the target. If it is absorbed within a couple of minutes and the surface starts to feel tacky, you were under, and the fix is more of it rather than a different product.
The honest measure is: if you are not slightly surprised by how much you used, you probably used too little.
Using too much is not a real problem. It is messy, it needs a towel, and it costs a little more per session. Using too little causes pain, small tears, and condom failures, which are all considerably worse outcomes than a wet towel.
Why water-based needs topping up
Water-based lubricant does not stay put. The water in it evaporates or is absorbed, and what is left is the polymer carrier, which feels sticky rather than slippery. That change happens on a timescale of roughly ten to fifteen minutes, faster in a warm room or with friction.
The important part is what that transition means. Sticky is not "used up and still working" — it is actively worse than nothing, because it creates drag where there was none. Adding a little water can rescue it briefly. Adding more lubricant is the real fix.
Silicone-based does not have this problem. It does not evaporate, so one application lasts, which is why it is the better choice for anything long. The trade-offs are that it is harder to wash off and it does not belong on silicone toys.
The mistakes that account for most of it
Putting it on the toy instead of on both surfaces. It needs to be on both. One dry side against one lubricated side is still friction.
Adding water to stretch a water-based one further. It works for about a minute and then leaves you with a thinner, stickier film. Water is for reactivating, not for extending.
Using less because it seems like a lot. The bottle is not expensive relative to the thing it is protecting.
Not reapplying because interrupting feels awkward. The interruption is ten seconds. The alternative is discomfort that ends the session anyway.
Assuming one type covers everything. Water-based is the default because it is compatible with silicone toys and condoms. Silicone-based is for length and water. Oil-based is compatible with neither of the things that matter.
The amount changes with what you are doing
The teaspoon starting point is for the straightforward case. Three situations need noticeably more or a different type.
Anal use needs more, and needs it reapplied. The tissue does not produce its own lubrication, so everything has to come from the bottle, and what is there gets absorbed rather than staying on the surface. Whatever amount you think is enough, the usual advice is to use more than that. Thicker water-based formulas are made for this and hold up better than the thin ones.
In water, water-based is the wrong tool. It rinses away almost immediately. Silicone-based is the one that survives a shower or a bath, which is most of the reason it exists as a separate product.
With a condom, the amount is asymmetric. Plenty on the outside, where it reduces friction and breakage. A small amount inside the tip, no more — excess inside is what makes a condom more likely to come off rather than less.
On a toy, the material decides. Silicone and glass need very little because the surface is already smooth. TPE absorbs it and needs more, and it is also the material where using a silicone-based lubricant causes the most damage.
When the amount is not the problem
If it still hurts with plenty of lubricant, the cause is usually something else: a material that is dragging rather than the lubricant running out, an infection, a skin condition, or dryness from medication or menopause. Those are not solved by more of anything, and they are worth asking a GP or a sexual health clinic about rather than working through a product page.
Persistent pain during sex is common and treatable, and it is not something to solve by buying a different bottle.
Questions that come up
Does more lubricant make a condom more likely to slip off?
Excess on the outside is fine. Inside the condom, a small amount is enough — too much inside is what increases the risk of it coming off.
Can I use too much silicone-based?
It will not cause harm, but it is harder to clean off skin and fabric, and it can stain. Use less of it than you would of water-based.
Does lubricant expire?
Yes, and expired water-based is more likely to have separated or grown something. Check the date, and throw out anything that smells different from when it was new.
More guides
After menopause, what changes
This is the one situation where the answer to "which lubricant" is genuinely different, and the reason is a mechanism rather than marketing. It is also where buying only a lubricant is the most common mistake, because a lubricant is not the product that does the job.
Can lubricant cause thrush?
The honest answer is that some formulations are a plausible contributor and the evidence is uneven across the different mechanisms. The most useful thing on this page is not a yes or no, it is knowing which ingredient list to avoid and why.
Silicone or TPE
Almost every soft product in this category is sold as silicone, and a large share of them are not. The difference is not snobbery about materials. It decides how long the thing lasts and whether it can be cleaned properly.