The U.S. Transportation Security Administration (TSA) has updated its flight rules about what plane passengers can -- and can’t -- put in carry-on bags.

Last week, the TSA clamped down on liquids carried on board U.S. planes. Those rules came in the wake of a terrorist scare in England, with word of a plot to blow up flights headed to the U.S. by using liquid explosives.

Most liquids, gels, or lotions currently aren't permitted in carry-on baggage. Such items must be in checked baggage, says the TSA's web site.

But the following may still be carried on board:

--Prescription medicines with a label that matches the name on the passenger’s ticket.

--Baby formula and breast milk, if the passenger is traveling with an infant or small child.

--Up to 8 ounces of liquid or gel low-blood sugar treatment.

--Up to 4 ounces of nonprescription liquid medications.

The TSA will also require all passengers to remove their shoes for X-ray with carry-on bags.

"I think it's important that people understand that they can bring their medications, including liquid medications,” Phyllis Kozarsky, MD, tells WebMD.

Kozarsky is a professor of medicine at Emory University School of Medicine and the medical director of TravelWell, a travel health program affiliated with Emory Healthcare.

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Travelers Tips

Here are 11 steps passengers can take to make their trip through security as uneventful as possible:

1. Leave pills in their original bottle; don't mix different pills in the same bottle.

Travelers often put pills in one large bottle, and they're not labeled, Kozarsky says. That's not a good idea under the new rules.

Fliers "need to realize that they have to save the bottles and bring them with the labels," says Kozarsky.

2. Check the name on each prescription bottle.

Does the name match your own? It must, under the new security rules.

Of course, you shouldn't be taking someone else's medicine. But if you had a name change since getting the prescription filled you might want to visit your pharmacy to update it.

"I would think that if you went to your local pharmacy and asked your pharmacist and gave them your identification, and you had your insurance card, they probably could make up a new label for you," Kozarsky says.

3. Don't bury medicine bottles in your bag.

Put the pills in an easy-to-reach spot so you can get them quickly for security checks.

Minimizing clutter in your carry-on could also make security screening easier, says the TSA's web site.

4. Pack your patience.

"Just realize that you're going to have some waiting time," Kozarsky advises. "Bring some good reading material and try to be patient and relaxed."

The new rules may not run smoothly right away, so some increased flexibility in dealing with the procedures may come in handy, Kozarsky says.

5. If you're not feeling well, speak up.

"People certainly should always open their mouths if they're not feeling well, and tell somebody," Kozarsky says.

Airport wheelchairs may be available, and some airports have medical clinics. Also, a fellow passenger may be a health care worker.

"Usually within an airport ... they will have somebody who is able to respond to a medical emergency," Kozarsky says.

6. Contact lens wearers, take your glasses.

The TSA's web site permits "essential" nonprescription medicine to be carried on board. But it doesn't define "essential," so items like contact lens solution fall into a gray zone.

"It is open to interpretation and it will be interpreted by a screener there," TSA spokesman Darrin Kayser tells WebMD.

"We are recommending to everyone that if you absolutely don't need it on the airplane, please put it in your checked bag," Kayser says. "If you do absolutely need it, then you'll need to sort of explain that need to a security officer.

"I would think that it would be best to put that [lens solution] in your packed luggage, and to take your glasses, just in case you can't find your contact lens solution at the other end."

7. Asthma inhaler? Check it, if possible.

Aerosols are banned from carry-on bags under the TSA’s latest rules.

Remember the general rule of thumb: "If you're not sure, put it in your checked bag. If you have to have it with you, then you'll just need to have a conversation with the security officer and explain why ... you need that with you," Kayser says.

"I understand with inhalers people may not have the [prescription] documentation with them," Kayser says. It's going to be very helpful to our security officers if you do have the documentation. If you don't, it's going to make it a little more difficult."

"My wife used to have asthma and occasionally has an inhaler," Kayser says. "If at all possible, put it in your checked bag so that ... it just makes things easier."

8. Hand-cleaning gel shouldn't go in your carry-on.

Moms find these gels particularly helpful in keeping tiny hands clean away from home. But they won't make the cut at the security checkpoint.

"Put that in your checked luggage instead of carrying it in your purse or your hand luggage," Kozarsky says.

9. Don't worry about baby formula.

People flying with babies won't need to sip from Junior's bottle for security's sake.

"TSA will not ask passengers to sample fluids or beverages during the screening process," says the TSA web site. "This process is being required at foreign airports and is not required at any domestic U.S. airport."

However, infant formula must be submitted for inspection by TSA officers.

10. Flight crew should still be serving beverages on board.

"There are still in-flight beverages," the TSA's Kayser tells WebMD.

"It's only a prohibition on bringing beverages in. But there are still beverages on the aircraft," Kayser explains.

11. Know your limitations.

"People who will have trouble waiting for prolonged periods of time -- if they can -- may want to delay travel until things settle down, especially if these people are plagued by anxiety," Kozarsky says.

"If they feel that they're not going to be able to handle it because they won't have their own bottle of water, and will have to wait for service, or they will have trouble with the extra hour that they may have to be standing somewhere, or the lines, or whatever," Kozarsky says, "then people need to be realistic about what they can handle and delay travel, if that's what it's going to take."

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By Miranda Hitti, reviewed by Louise Chang, MD

SOURCES: News release, U.S. Transportation Security Administration. U.S. Transportation Security Administration: “Prohibited Items.” U.S. Transportation Security Administration: "Immediate Changes to Airport Screening Procedures." U.S. Transportation Security Administration: "Banned Liquid Exceptions." U.S. Transportation Security Administration: "Infant Formula or Milk Sampling." Phyllis Kozarsky, MD, professor of medicine, Emory University School of Medicine; medical director, TravelWell. Darrin Kayser, spokesman, U.S. Transportation Security Administration.