A FEW THINGS IN LIFE are just plain uncomfortable. For instance, I get really uptight when I'm stuck in traffic. And if it's dark and rainy, my discomfort increases dramatically.

I can think of another situation that would make most of us really squirm: standing in line to buy something and then having your credit card declined. And if a long line of customers is behind you, then the discomfort doubles or even triples.

The good news is that there's a limited number of scenarios that lead to this awkward situation. And most of them have an easy fix.

Up ahead, I'll cover the following topics:

• Six reasons for having your credit card declined.
• How to react when your credit card is declined.
• What to do after you get home.

Six Reasons for Having Your Credit Card Declined

Let's take a look at the most likely reasons you might hear the dreaded words: "Sorry, but your credit card has been declined."

Your credit card has expired.

It still pays to open the (snail) mail. But if you're behind with your personal paperwork, your new card could be sitting in your home somewhere.

If your new card isn't anywhere to be found, it could be lost in the mail or stolen. You need to call your issuer right away and report that you haven't received the card.

While you're on the phone, confirm that your issuer is sending you a new card. And start opening your mail every day!

Your account has been flagged for fraud.

issuer knows your account has been compromised. Always call your issuer quickly to determine what has happened.

It's also possible that your card was flagged because of what the issuer considers "suspicious activity." This could mean that your card was used to purchase an item in an unusual location. For instance, if you live in Boston and you suddenly make a purchase in Bangkok, your issuer might worry you've been hacked.

To prevent your card from being flagged for fraud, let your issuer know when you'll be traveling away from your normal haunts. Having your card declined is uncomfortable, but losing access to your credit card when you're a long way from home is enough to ruin a trip.

Your card doesn’t have enough available credit.

Sometimes, this is an innocent mistake. You used your card to hold a reservation, and a portion of your credit limit is still on hold.

But if you've maxed out your credit card, that's more difficult to resolve. If you didn't opt in to over-the-limit fees, then when you try to buy something that exceeds your credit limit, your card will be rejected.

And, trust me, that's a mercy rejection. If you've used up your available credit, it's way past time to step away from your credit card.

Face the balance on your credit card statement and determine how this happened. If this is a temporary problem, call your issuer and talk to the hardship department. Someone there might be able to help you out on a short-term basis, which could mean a reduced annual percentage rate or lower minimum payments for a year.

Your card payment is past due.

This can happen because of poor money management or insufficient cash flow. The key is finding the root cause so you know how it happened. Sometimes, setting a budget and tracking your spending takes care of sloppy payment habits.

But if it's a cash flow issue, you need to go through your budget and cut some expenses, even if just temporarily. Call your issuer to report that you're catching up on your payments. If you get current with your account in less than 60 days from the due date, your late payment may not be reported to the credit bureaus.

You charged an extra-large purchase.

This is an interesting one because it can happen even if you have more than enough available credit for your purchase. This is similar to making a purchase while on a faraway trip.

Unless you make large purchases often, this type of transaction is outside of your routine. Your issuer could worry that someone has stolen your account numbers or your physical card and has gone on a shopping spree.

If you plan to charge an expensive item, such as a used car, call your issuer beforehand. Then the issuer will know the purchase is legit when you request authorization.

You entered the wrong account information online.

I actually did this a few years ago when I decided to do my Black Friday shopping online. I wanted a new leather jacket, but only if I could get one for half-price. I'd already picked out the one I wanted and was just waiting for the discount early on Black Friday morning.

Only one was left in my size, and I panicked. I typed so fast that I entered the wrong account number. I realized my error and, fortunately, still got the jacket.

It's also easy to key in your security code wrong if you're in a hurry. If you're sure you haven't made a typing error and your card is still being declined, then call your issuer and ask why your card was declined online.

How to React When Your Credit Card Is Declined

It's possible to weather this uncomfortable situation with grace and aplomb. If you think you didn't insert your card's chip properly and want to try again, that's fine. But if your card is declined a second time, your choices are limited to the other cards you're carrying at the moment.

If you don't have a backup, depending on what you're trying to buy, you can ask the merchant if you can put the items on hold until you fix the problem. Or you could return with a different credit card.

What to Do After You Get Home

You need to call your issuer as soon as you can and find out why your credit card was declined. You might be told that your new credit card was mailed to you last month. Or, if fraud is suspected, you might be asked to verify purchases before your card can be used again.

Sometimes, it's more complicated than having an expired card or a false fraud alert. If you've missed a payment, get your account back in good standing before it damages your credit.

Whatever the issue, be sure you stay on top of the situation until it's resolved.

This article was originally published by Beverly Harzog, creditcards.usnews.com.